Hello Ivan, the typical reversing unit (20824) in my experience draw about 70 to 80 mA all the time the loco is running. Therefore, at a medium speed running at around 12v the coil in the reverse unit is dispersing just under 1 watt of power. This will make it warm up a bit.

I've never really considered the heat in the unit. I have that same loco so I will give it a run for a while and see how warm or hot mine gets.

I'll post again later today.

Paul

Ivan - this morning I ran my 3147 around for 15 minutes with a train of eight tankers.
The reverse unit was warm afterwards but I wouldn't describe it as hot. This loco runs well with a moderately low controller setting - I think around 10-11 volts.

Since you connected it to 15v the current through the coil would be proportionately higher so a bit more heat would be expected.
Due to the way these locos are wired the reversing solenoid is energised all the time the loco is running. The spring prevents the reverse switch from moving below about 22 volts or so but current is still flowing through the coil - just not enough to overcome the spring and operate the switch.

It sounds like your loco just needs a bit of a service with adjustment of the reverser spring.
From what you describe I would think it will be fine after that.

Good luck with it - it's a great loco with that lovely 'floaty' motion that is typical of analogue AC locos.