Heavy, Carl, hi, thanks for the replies, appreciated.
It's been chucking it down with rain today, but I managed to give the bike a quick clean down with "Gunk" - and it's looking a little cleaner, yay! - and I've also sprayed the 'stucksolid' saddle stem with PlusGas - and it came out a treat
Having since given the bike a hose down and tipped it over there seemed to be no 'brown death' pouring out afterwards. At least I think that's what another member elsewhere on RetroBike called it, I guess they meant rust of some sort in the frame.
The derailleurs both seem to work ok, although one of the brakes is sticking a bit (it's VERY early days with the clean up though and haven't even started taking anything much apart yet) but they're no longer black with grime...
...BUT when turning the crank (the left one is missing) it seemed as if the chainrings were not perfectly round
! A few googles on Suogino Cycloid 110 48T chain rings, however, and it seems it's designed that way
I'm guessing you knew that already...
I'm intending to post again when I've made some progress, but thanks again, very glad to have found this forum!