I have so many reps pass through my hands. One of the first reps I have is an AP Jumbo. I still have it and it runs no problem. Majority of A7750 I have had did not have any problem until 3+ years. Lately, one arrived and after a few days it went dead. The problem is always the same - the movement is full of dirt and dry. So if you really like the rep you have, get it serviced and it will last longer and keep good time.