To me there are two major items:

1) Condition of the ball and the amount of games it has on it...think of a used car.

2) The current drilling.  If the drilling is something that I would like then the changes are minimal.  If the drilling is something out of your ordinary layouts I would consder where the new layout would sit in comparison to old.  I personally never liked putting plug in my track yes the material if done correctly could be perfectly round and flush to the surface, but that would depend on your pro-shop and their ability to do a plug job correctly.  The other thing that I never liked is to put plug material in the bridge.  Yes it can be o.k. but it's something that I still try to avoid if at all possible.
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-Chris: DJ's Pro Shop : Auburn, MA

Edited on 9/23/2009 6:51 PM

Add to the above possibly where the current drill is and how that's going to impact anything you want to drill.  I know my driller is great at getting the plugwork nice and level and even with the ball.....but if you have a switchgrip there and that's right in your potential track......and if not leveled out....you will know it.

If older stuff, I will look at the logos and all to see how intact they are.  That might indicate use....or excessive resurfacing if not present.
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