You are talking about the relay Are you not? Initially I thought you were talking about the motor. The relay directs DC, if the swing touches the magnet it may have a period of magnetism and stick. I suggest a piece of electrical tape. Some may be adjusted to not touch at all.
I wish I could show you but I cant post a video on this site any more. Yes relay, ie a coil around a magnet. It lets go but... it flutters and arcs. Points are clean and motor brushes measure .1 ohm, hardly a big draw there.
T-man, don't have a youtube account but that got me thinking. If I did I would get a million more replies and I would not need this forum anymore. Its evident this site is strapped for storage.
So my 616 has new brushes, e-unit drum and fingers yet when I dry to run it and it hits a spot in the track (not a bad piece) it stops and tries to cycle. Now the strange thing is when I put it in to manual mode, it goes forward, hits a piece of track, buzzes and tries to go into reverse. How is that possible?
If your 616 stops at a certain track, there is a loss of voltage getting to the loco. It could be a bad connection to that track at the track pins, or a dirty track. Check also that the loco wheels and pickup rollers are clean; clean them with Naphtha if needed.
If your 'E' unit cycles at both positions of the lever, there is a problem with the 'E' unit lever not making contact on the fiber board to lock out the coil from cycling, or the 'E' unit itself is not cycling properly and needs repair.
I store my videos on you tube without discussions. Any questions I direct here and just link the video here.
I did the same thing with foto can , that did not work well in the end.
The loose lever is a possibility. I insert a piece of spring from a tape measure to tighten it up. The force of going in circles can move the lever. Try going in the reverse direction. Let the force work for you to test the theory.
Rule out the possibility of track feeds being cross wired If you are using insulated blocks. Accidental e unit switching is cause by a loss of power. This could be a simple area of corrosion to cause it. Normally I run the engine a lot in just forward to eliminate this possibility.
The bottom of your relay that pivots up and down is your relay armature , if after adjusting its closing point with no success try adjust the other end of it (follow its metal plate straight back ) just a tad downwards just a little bit and test it. By adjusting it your can lesson the upward tension on opposite point that is not fully closing.
For your tender check the 2 wires coming out of the relay one comes out and is soldered to a lug on the back of it the other wire comes out and is soldered to bottom lug on front of relay.
In addition to 2 other wires up top soldered to their lugs follow all the wires and make sure the solder joints look good otherwise re solder them.
Hope this helps aplease post back what you find loose solder joint, needs adjustment etc.
Like to add when looking at brush plate with whistle engaged the motor should turn counter clockwise otherwise not much whistle if any at all even though not your problem it may help others as wires easily get crossed i have done it !