Gritty or slimy cables can be a problem. Clean or replace?

Pulleys can wear out. More often, they malfunction because you didn't clean them. Ever.

Cleaning out an old front fork.

Old-fashioned threaded headsets, and how to show them love.

Lubing a shock wiper. (The cleaning is the important part.)

Not rocket science. If you're having trouble pumping the tire, maybe the valve is full of crud.