I have a bizarre question - what is the green translucent grease that seems to be used in Studer/Revox tape machines and for what purpose? I have spent hours in the past cleaning a Revox PR99 and a Studer A80, bought in different countries at different times, from this horrible sticky substance, and a few A80 parts I just received from Ebay also have the same substance. Happily it can be removed with a cloth slightly damped with alcohol. But I can not understand the coincidence!