Oddisheru,
Have you tried running any motorized units on the switch? I have found that the problem does not occur on all units, but seems to impact more modern units (I have post war locos, and modern TMCC units. It's the latter that spark.)
I would also add that I purchased 3 more of these switches in November at a great sale price, 1 of which was a RH 072 hoping to eliminate the problem - same problem with new switch. Back to electrical tape.
Michael