[Radio Wrangler]

If it and even its plastic cover have survived the baptism of fire which is shipping, it's a natural survivor and deserves some effort.

Put it on one side and give it a break, as Ted suggests.

When you come back to it, stuff a signal into only one channel. nothing into the other, then go probing along the channel that should be quiet. Go slow, go steady, go methodical and you'll get there.

My style of fault-finding is to test and measure the living daylights out of the set until I'm sure which component is duff, and then replace just it.

Your style seems to be to work your way through by changing likely candidates.

Both methods work, but each has drawbacks. Mine is tediously slow, too slow for a commercial repairer. Occasionally I can't decide between multiple parts and have to change the bunch anyway. The keep changing things approach can be much faster but it runs into trouble if spares aren't easily available, and it doesn't always show you how the fault occurred and it can get stuck when one part can take out another.

Whatever someone's style, it's helpful to be able to switch to the other when a job needs it.

David