Yes, these are prone to cardiac arrest.
But, I've become quite successful in resuscitating them....thanks to Dave at NWSL (NorthWest ShortLine).
So, here's what I've discovered along the way.....
1) Most frequent cause of malfunction is the small plastic gear on the end of the motor shaft. The production version is plastic....destined to eventual failure: the gear splits and becomes loose on the motor shaft.
No problem...if you're willing to spend about $10 for a new METAL gear, ream/drill the I.D. thereof for a proper light press fit...or, less desirably, VERY close slip fit with a drop of CA to secure...and properly support the motor shaft when the gear is pressed on. The NWSL correct part is 37410-6, a 10-tooth spur with a 1.5mm bore...the latter requiring sizing up to the motor shaft diameter.
Oh yes, be sure to note the correct position of the gear on the motor shaft....the new gear should be essentially flush with the end of the shaft.
2) Noisy gears are most often associated with the failed/failing motor gear and its mesh with the larger ring face gear. In some cases I was able to create the grinding noise AFTER I replaced the motor gear simply because I had not been careful in re-positioning/assembling the motor back into its cradle in the base housing....a correctable embarrassment! I obtained a quantity of DOA crossing gates from a chap, and found a few noisy gears.....the result of very evident tampering (opening up, poking about) with the motor mounting.
3) The third cause of cardiac arrest is too much tampering and over-adjusting of the limit contacts in the housing in which the crossing gate rotates. In fact, my personal experience with these gates on my layout is that, if the gates start to act up, DO NOT rush to play with the limit screws on the gate housing!! FIRST, check the gear on the motor shaft. Actually, I've found the factory setting of the motion/lights limit screws to be quite accurate and needing no further adjustment. In any case, rotating one of the limit screws more than a couple degrees is asking for trouble, more than solving a problem!
One reason for NOT getting quickly into the crossing gate housing is that the arrangement of gears/cams is VERY fussy, having unique orientation and positioning. I tend to consider a problem traceable to this housing and its complicated internals as the final death knell....not worth the trouble/aggravation to fix.
4) BUT!!!....even if you give the crossing gates their last rites, you can usually salvage the flashing lights. It's not too difficult to disassemble, excise the specific parts that relate to the gates and their motion, saving the lights and circuitry. The gaping long hole in the middle of the shaft can be closed up with some plastic tubing cut to fit and painted silver to match the rest of the assembly. Voila! Flashing lights....with out gates! Need sound? Look up ITT Products and other sound chip/circuit providers for a crossing bell sound, add speaker......voila, voila! Lemonade from lemons!!
OK.......so that's what I've learned...in part. Why MTH hasn't stepped up to a metal gear on the motor shaft is probably an issue of cost. But I personally think it would be a customer satisfaction improvement in the longer run!