The Turbo on my latest acquisition (a nice Indy 500) would occasionally jam the pinball between the exit and the blades of the turbo. It was worse on multi-ball launch (sometimes the ball would jam the turbo blade to a stop) and you could hear a slight catch on single ball launches. I knew it was only a matter of time before one of the blades broke off. Seeing as they are made of unobtainum, I decided to scour the Internet to see if this was a common problem with a known fix.
Low and behold, I found an ancient post that described a possible fix. Thought I would repost it here for the pinside crew!
Simply add a washer on the motor shaft below the turbo impeller. This raises the turbo blade and allows a clean exit for the ball. Took me all of 30 minute (I did some cleaning while I was in there).
I did it to mine and no more jams through 10 games or so.