When I got my Slamdance I gingerly tested the ankle and it felt solid, so before I even attempted to transform him I squirted all his ankle joints with WD-40 and let it sit for an hour. Worked a treat, feels very loose yet secure now. I still make sure not to be ham-fisted with him however.
That's the cheapest I've heard of Ghostbusters Optimus - however I have no way to get him from Hong Kong sadly :(
Anyone know anywhere else to source Redwing at a decent price?