Hi,
Since my last answer some further changes have occurred. The replacement of the PCB was only a temporary solution. The same problem is there again. I have abandoned using the camera, even if it still shoots very good photos when zoom is not required. Two persons in the chain have had good results by using Kontakt 60 Reiniger. Is wd 40 something similar? There are also risks in using chemicals, but if you are ready to take them, you could at least try. Use a very small amount of the chemical at least to start with.