i use to drift right and i know alot of people who still do. i use to look at my target and drifting toward it (drift right cuz imma right handed). i fixed it by squaring up my shoulder being more parrel wit the foul line and actually consciously force my self to drift left. I cant say its a solution but it done the trick for me i now drift 5 boards left and improve my game big time.

Also try to be aware you are "walking the tightrope" on your approach. Personally if I do not keep this in check, my approach is something like Frakenstein's monster and drift all over.

I used to drift 3 to the right consistently. It made 10 pins a little more tricky than necessary. Because I have a 5 step approach, I make sure that my second step (right foot) is place directly in front of and in line with the left foot. Now I have zero drift and can create better angles to the lane.

Another 2-cents:

When bowlers are playing straight up the boards, it is easier for them to maintain that "tightrope" path.  As we start moving in playing deeper and deeper with stronger equipment, we will still try to walk to our spot and thus drift slightly toward the target. 

I would maybe try balling down, especially on house shots, and see if your drift is associated with playing too deep.  Doesn't mean you can't play deep, but at least you will know what the issue is and a good coach can come up with fixes (i.e. swing plane and open/close positions with the upper body).

Unless the drift is extreme, I wouldn't worry too much about it, assuming you can end with the exact same drift every time.  I doubt a high percentage of pros can end on the exact board they started on.

Excellent points, Avabob. There is a world of difference between the footwork mechanics of the older strokers (of which I am one) and the power players of today.
Dick Ritger was another "right-drifter", by the way.

As for the crossover step, I am a firm believer that caution needs to be exercised
when attempting its use. For most (but not all) old time strokers, the crossover
step can actually be a detriment to developing a consistent, mechanically sound
approach. It is often stated that a crossover step is necessary in order to clear the hip on the backswing. In the overwhelming majority of cases, this is not true for
strokers. It can often cause inconsistent drift and a misaligned swing, both of which
dramatically decrease accuracy---- a fundamental "must-have" for the stroker.

Power players on the other hand, rely much more on it because their games
accentuate power over accuracy. Their hand tends to be more under the ball
which requires getting the bowling elbow towards the inside their bodies. As you stated, this also
gets them in the position to project the ball more left-to-right. This, along with
strong lateral spine tilt allows the wrist to more easily collapse at release.

For these reasons, I never advocate the use of a crossover step for old time strokers
unless there is a physiological reason for doing so--- a rarity, or if they are wishing to
convert to a more traditional power game. Granted, there are examples of strokers
who in fact, deploy  the crossover step. The successful ones have managed to
overcome the asymmetry that comes with it. Not easy to do. Many previous PBA
players (strokers) never used a crossover step ( Mike Durbin and John Handegard are just 2 examples).

When old time strokers need to move in, they will, in most cases, fare much better
by realigning both feet and shoulders so that it will allow them to maintain a 90 degree angle with their shoulders and follow through.

I concede that this is often a hotly debated topic among even the very best and respected bowling instructors of today. However, in my50 years of bowling,
I have come to the conclusion that more often than not, the advice that is given
needs to take into consideration the stark differences in bowling styles between
yesteryear and today. What works for the old stroker game is often detrimental
to the power game of today (and vice versa).  I have a tremendous amount of
respect for many of the contemporary instructors who regularly contribute their vast warehouse of knowledge to publications like BTM, etc. I have learned a lot from them.
However, when it comes to advocating the crossover step universally, I must respectfully disagree. For the old time stroker, there are still a lot of things that Bill Taylor got right, including the use of "of perpendicular lines --- advice that applies
as much today as it did back then.

As far as drift, I also agree with the previous posts that basically said that if it is not too extreme, there is usually not much to worry about. I would add that if the drift
is inconsistent, if it impedes a free-flowing consistent swing path, or if it causes the bowler to lose leverage, then drift can become a problem. Excessive drift can also
limit a bowler's ability to play all parts of the lane. Also, bowlers who drift during
their approach will result in decreased (or increased) forward ball velocity to some degree.  Right drift, as Avabob states, was/is very common among us old time strokers. It is also true that most right drifters have fairly straight trajectories.
In many cases, this was the direct result of "filling the hole" at release (closing the gap between ball's laydown point and slide ankle. This was quite important in the days where accuracy trumped power. Indeed, stepping left (for a right hander) on the slide step would cause the laydown point to be farther right of the slide ankle. This would
cause the bowling elbow to chicken wing, or the entire bowling arm to move to the right---away from the body, resulting in both a loss of leverage and accuracy. It was
known as "stepping out of the shot". This still causes the same problems as it did back then but today's powerful balls can sometimes overcome sopme of this. Not so then.
Even in today's environment, the classic stroker still must depend on "filling the hole"
more so than the power player.

Perpendicular lines are still very important to
strokers, but not so with players like Devaney, Rash, etc. Their games require different rules than ours. It's important to know the difference.