Simple Hornby servicing/repair advice needed

I've got my 00 layout up and running after a year or so dormant, but have found my locos are a little worse for wear: namely 3 with traction tyres that have loosened thus giving no traction, and an old style A3 that has lost drive to the wheel altogether.

My questions being:

1. Where's the best place to order Hornby spares from? Any recommended online dealers or locations in the midlands?

1. My Hornby A3 has a Ringfiled 5 (pole) motor in it, the one they seemed to utilise for everything a while back and although the motor runs well it doesn't propel the loco anymore - the smallest gear, on the motor shaft is very loose and so the drive shaft spins but doesn't transfer motion to the larger gears connected to the tender wheels. Was it always a friction fit? If so, do I need a new one of these gears or just some grease of some sort?

Thanks

Robert C