MTH RailKing RS-3 Diesel Engine Odd sound issues - Battery?

The Tenergy battery is better than the original Protosound battery  That isnt the problem  What it sounds like is that somebody removed the PS2 and installed TMCC if it has a program run switch  Can you post a picture of the boards

Thanks for the info; I will remove the body tomorrow and post a picture of the boards. All sounds, horn, bell, engine running and shutdown sounds, seem to work, just loud and distorted.  Craig

“ Used, mint condition” is an oxymoron.

Sounds like the previous owner(s) have been dabbling with the engine. FWIW- I never buy an engine unless I can see photos of the underside to check the condition of wheels, rollers, presence of screws, etc.

A couple photos and a video of the sound issues would be helpful too.

Volume pot is located under the long hood truck.

Thanks for the support and information. Thank to RSJB18 for the photo - on my engine where the volume pot should be there is a switch in that hole with the descriptor "run - program.  As Bluelinec4 suggested, the previous owner may have removed the PS-2 board and replaced it with TMCC boards. I do not have time today to remove the body but did locate the source of my distortion.  Wires were touching the speaker cone and impacting the cone movement.  Pushed the offending wires back up through the hole into the engine, reattached the fuel tank with the two correct screws and vola, no distortion. Horn, bell, engine and shutdown sounds appear to work properly. I will find 2 additional screws that fit, not using that oversized machine screw.  I like Mark's comment on "used -  mint condition" being an oxymoron.  Also, don't think the RS-3 likes the Lionel CW80 very much; when I added lighted passenger cars the CW80 blinks red, calls 911 and things shut down.  When I finish the new layout, I think the Z4000 will do the job. My other diesel, Lionel GP-7 had the same problem with the CW80 but ran well with the Z4000.  We'll see. Thanks again; more later. Craig

Protosound and CW-80's don't play well together at all. Then again, CW-80's barely play nice with Lionel engines

Glad you found the issue with the sounds.

One only has to look at the waveform out of the CW-80 to see why it doesn't play well with lots of equipment!

Yep, think I'll retire the CW80 when the new layout is finished. That's an ugly wave form. Thanks for the view.