Ooooh, I hate those blue trimpots, I find they are almost always faulty in the TM500 gear I've repaired. I replace them on sight now...
Interesting. I've never had issues with them.
Yeah, not sure why I keep finding the bad ones. Usually the grey ones are ok, but I've had a few bad ones of those here and there too. Last one was broken in the center 'axle' so the turny bit kept falling out.
Same here, I concur !
When I bought my 5000 series scope, found many of thes horrible trimmers on the two CRT boards. Half of them had fallen apart in the way you describe, knob falls apart because the thin plastic shaft holding it to the body of the trimmer just eventually breaks off, disintegrate, leaving you with no wiper because it's part of the knob !
Cheap horrible design.
So I went to replace them all, but to my surprise the pin layout and pitch was somehow unusual and I had difficulty finding a suitable replacement. Eventually found a brand and model that was identical, but hard to find. Since I needed many different values, I could not find any place in Europe that carried all the values I needed in stock. An Ebay seller would have one particular value, another would have another particular value, and Farnell would have 3 or 4 tops. Only Mouser IIRC in the USA had all the values available, so I resorted to paying a silly amount to import them.
So yeah, I HATE those trimmers too !