I've brought my old Hornby loco's out of hibernation (circa 1985 when they last ran), and all but one runs well after a wheel clean with the track rubber. The one in question is a tender driven 4P Compound, and it jerks all the time. I've looked at the wheels, and they look shiny to me, and I've cleaned and cleaned the wheels with the track rubber, but still no joy.
The tender on it's own seems to be OK (but i cannot be certain as I cannot run it on track on its own), but when joined up to it's engine, that's when the trouble starts.
I've also lubricated all the appropriate moving parts, and there are no broken gears etc.
Any ideas ?