I have a set of TS820 and VFO820 that suffer from the same problem. Frequency jumps. I already know the issue to be the wiper contact on a variable capacitor in the VFO. I cleaned it thoroughly, lightly lubricated it, and it works fine for a while. But If I let a week pass and try again, problem is back. Does anyone have any insight into this? I can clean, oil, and retention the little grounding wiper but it doesn't seem to be a lasting solution.