Here is the deal. Past two years my average has dropped. About that time I changed ball manufacturers. After the first year, I invested in coaching, and my average dropped more in the second year.

I hate to say it, but could it be the manufacturer / balls that I have chosen?

What should I do to increase my average back to a more respectable number? Buy another ball and see, or get it out of my head?

Almost to the point of retirement as it is not as much fun anymore.

Expectations seem too high.  Just because your average went down doesn't necessarily mean you are a worse bowler.  Did the league average go down also?  You shouldn't use average as the only criteria.

But if you are looking for a fix for a normal situation, I would look to fitness first.  Equipment is pretty consistent brand-to-brand (assuming adequate drilling services).  Coaching may or may not have helped, but I like to think coaching in general is a positive.  But as I age, I realize fitness is where I find has the best return on investment.

What were you throwing before and what are you throwing now?

How much of a drop have you seen?

Seeing less strikes but more spares?

My son has seen his average drop 20 pins for his hs season this past year. But they switched houses, had to replace most of his equipment as it cracked over last summer, and he just isn't striking as much.

Take a look at information you have available between then and now and hopefully you can find a reason for a part of it.

My average has dropped 11 pins this year but is currently climbing back up with 6 weeks left. 

In the beginning of the year, I was too slow to react to a change in the pattern - they moved it back from the foul line, making it longer (we were told for safety reasons...)  This gave me less miss room to the outside further down the lane that I could no longer take advantage of.  After the 7th week of league, I got my act together and figured things out and have been on the rise since. 

And although I've figured it out for the most part, unlike last year I have not been able to put together a really good scoring 3 game set.  I chalk that up to the lanes not being as soft as they were.  I accept the lower scoring conditions and try to make my spares.
 
Long story short tuckinfenpin, maybe it's environment related.  Maybe it's equipment related.  Maybe it's the matchup between the two.  You said it wasn't fun anymore.  I know when it's not fun for me I just go through the motions and throw the ball relying on muscle memory more than "working" for a good score.  Are you the same?  Sometimes the mental side is more of an issue than the physical side...

>> Here is the deal. Past two years my average has dropped.

You're probably just getting old. Hey, it happens.