"Bob C"

I have an old 12 volt 3 phase model railroad motor


** You mean 12volt 3 pole ?

Typically, 12 volt DC motors have 5 poles - with only three, arcing across
the comm segments will be severe with 12V input.

that has a dead spot
between two segments of the commutator.How can i fix it because to get a
replacement is almost impossible

** There may be a short between two segments or such a bad carbon burn on
one that current cannot flow.

Ideally, you need to trim the com by mounting the rotor in a small lathe,
but most times emery paper will do the job - long as the damage is not too
bad.



..... Phil