They sound pretty amazing but it's not the motors that are the problem, it's the decoder boards themselves that seem to be the issue. I am looking around for an alternative and currently leaning towards the ADS 8sx. R-
EDIT: Just found a photo of the SM3 on eBay. Very robust looking piece of kit from an era when things were made to last

. The Hattons PM-01's, which I am using, also sport that crank arrangement for operating other kit.
Young at heart. Slightly older in other parts.