[Milsurplus] ARC-38 chopper issues

[Ray Fantini]

I have spent much time getting my ARC-38 running, many hours have been spent cleaning and lubricating all the servo motors, bushings and rollers. Now the band switching, rack tuning and PA all work correctly and automatically. The companion 180L3 antenna tuner is still getting worked over, the chopper that feeds the servo amplifier has an issue. Think I have another bad chopper. The last radio I did was a 618S1 that is a 144 channel crystal control version of the 38 that had two servo systems. One tuned the slug rack and one for the PA deck and both choppers worked with no issues but on the ARC-38 both servo amplifier choppers were bad along with the third chopper in the correction amplifier for the SMO. Luckily I have an ARC-38A chassis that I have been striping for parts but now am out of spare choppers. The question is where the 400 cycle choppers a high failure rate item in normal service? The one in the 180L3 also appears to be bad. If you beat it with a screwdriver it will work for a while but then die again, looking at the chopper in the 180L it looks a little different than the ones in the radios but is it the same? The 180L3 I have paired with the 618S1 has a dead autotransformer so I disabled the servo systems in that and used it as a SWR meter and T/R relay for that radio but I wanted to have the fully working 180L with the ARC-38 but the chopper in the dead 180 appears to be just as bad. So do I need to start building up a supply of 400 cycle choppers or is this just an anomaly? Fair radio has several dead 38A chassis in their back room and wonder if I can buy all the choppers out of them?
Ray Fantini KA3EKH