I have just removed the motor from a small Farish N gauge loco (only 1 screw holding it in place) and found that a connection had come loose.   I soldered it back into position and now the loco runs very noisily!   One part of the motor became separated but just had to be pushed back into position and I'm wondering if the (plastic) cogs are not meshing properly - it's the first time I've even seen a motor let alone messed about with one!  :oops:    Any ideas please?

Ken.

Ken, is it an old Poole type chassis or something newer?

If it's a Poole type then it should run  out of its body a couple of wires, one to the chassis metal the other to the wire across trhe top of the motor,  allowing you to hopefully check  where the noise is coming from. I've not had much dealings with more recent models.

It's certainly an old one Mike - and your favourite SR too - but it didn't have any actual wires, just a wishbone shaped connector with the two arms emerging from a yellow waxy disc 6mm or so in diameter and it was one of these that had come adrift.    I could open it up again (oooh!) and take some photos if it would help?

Ken.

The yellow waxy disc is a ceramic capacitor and is there for radio/tv interference suppression from the sparking of the motor. It is more of an issue in the UK than it is here in Australia but there are areas here where it becomes a problem. I do not know the motor design myself but I understand that the motor design is fairly "pedestrian".
Loosen off your screw and replace the motor again. It may be that with the finer tolerances even a hair will cause a worm (what many call a worm gear) to sit tight on the main worm gear. Also you may have upset the lubrication and the position of the brushes. Reseating it might do the trick making sure there is no hair or something the cause the motor worm to mesh tighter… yo too like me might need a magnaviser!
Cheers 
Trevor

Thanks Trevor, I'll check that out (brushes and hair eh - well they go together don't they?).  :roll: 

Ken.

Careful with the teeth on the gears as well !!!!  Especially your teeth!!!
Cheers
Trevor

Years ago I picked up a simple way to adjust the worm/gear. Use a thin piece of paper, put it between the worm and gear, set everything up by eye, fasten down the motor, then ease the paper out. This should give a good setting for the loco. :)

I just noticed the post date!
Did you sort the problem out Ken?

ATB
Shaun.