Yeah, my previous radio was an M8 that I ran for a long time. I had the opportunity to switch to a 4PKS-R while being able to gift the M8 to a friend. He still uses it to this day. That radio lived in a Trinity foam case. When radios get a lot of hours parts wear out.
Chuck, contact Futaba about the problem you are having with your 3pk, you probably could fix it yourself if you can get the parts.