How do you characterize "oscillation" ? What is oscillating and what are the necessary elements(certain power levels,etc) that need to be present for your "oscillation" condition to be present ?
The issue I have is when the rig is keyed and held keyed, the transmitter will react and not output power until about 500ms later. Every instance of keying will sometimes exhibit this. I also read that the PRO II models had some sort of "dit clipping issue" which was resolved fully in the PRO III. What caused that issue ? Are you familiar with this ?
This sounds like the common oscillation issue, usually due to a faulty RFRX-muting circuit (Q25, D22, D23 on the CTRL Unit), and possibly a bad diode or two on the RF Unit (D104, D801).
The oscillation is usually most noticeable on 6 meters, but it can also affect 10 and 12 meters.
The component damage is usually due to an ESD event, or RF-overload from a nearby transmitter.