I'm going to pull out the internal circlip and release the imprisoned nut, but only to completely clean all the corrosion away and coat it in lubricate as if ones going to do it you might as well do it properly.
BTW Blue, do you actually own a HT GTS ? as I've built a concourse HG (original restored category) but in Premier format, both variants 186 manual in Vedoro Green Mk II and 253 T Bar in Burnished Bronze.

Cheers,
BB.

I live a 24 Hour lifestyle, but every now and again I seem to fall asleep, well at least that's what my wife tells me.