Hi, Malc,

The only way is to increase the PWM frequency ( 500 or 1000 Hz might be enough ).
also Think to the minimum PWM ratio zone to skip ( ~ 10 % )

you'll find a problem here : some motors do not like high frequencies ( > 3000 Hz ) due to their high inductance ... and might overheat.

Do you think I could make a test with my Big Boy, die cast "crocodile" or JEP 231 ... or some oldies ???

Hé,hé ... my father gave its life and brain to our national railway company ...and still builds custom models ( 84 years ...the papy !!! )

Alain