Welcome to the wonderful world of open frame AC motors, the smell of ozone, and the delightful buzz of e-units ....making sure your 2046 is in proper tune, and the whistle tender are key....couple things to easily check, be sure the track, the rollers ( on both the engine & tender) are good and clean & lubricated....check spring tension on the arms,...you can put a tiny drop of oil on the roller pins, and the pivot pins of the collector....the arms should make good solid tension on the rails, loose or distorted arms make the rollers lose contact, thus the roller will jump around making sparks, and tiny little char marks wherever you go....so be sure to clean the track as well.....yes & no as to this problem making the tender blow inadvertently......dirty and or loose rollers, dirty wheels, can make a whistle “trip” on occasion....clean wheels, clean roller pickups, again, a small drop of oil is ok, and also a tiny drop of oil on the pivot points where the tender trucks meet the tender frame helps.....remember, the path has to go through the wheels, through the trucks, and through the frame....so that’s a few places contact can be lost and re-gained at any given moment....
Pat
