[Plump Kibbles]

Not really a rotating motion - shouldn't rotate at all. Maybe the loose bolt - if so. Might pivot a very small bit; plus with the weight pushing against the assembly, anything in there for lubricant is going to be pushed out eventually.

It could be anything causing the squeak, even a low weight lubricant - keyboard exchange doesn't provide a high level of detail sometimes to really dive into the technical aspect as disassembling.

Mikegolf: How many miles are you on; have you had the suspension at all serviced besides the linkage? I'm just willing to bet there's a dry spot that was found after movement that settled into a squeak.. Just me!