Gadge,
Much thanks for your reply.
I'm glad I asked as before doing so I assumed that it's likely grease - as like I said I have several rear SP mowers and all of them when I bought them 2nd hand had grease liberally spread in this area. And even when googled every post I found on the matter said to use grease and made a point of saying it's bad not to. Just goes to show that you can't believe everything you read.
Your advice lines up with what I vaguely recall someone here stating was in an old Victa workshop manual, which was not to apply any lube but just to blow out any dust/debris.
Do you have any idea about whether it makes any difference how slowly or rapidly you engage the drive mechanism for these such driven units? I mainly ask for a few Victa 550 Pro's.
Thanks again for your great reply.