There is an old post where I have photos. Case has four screws. Just can't figure how copy. 6/04/14

Not sure about button but I am sure they have a replacement part.

Knowing the button covers are removable and the same buttons as used in Zcontrollers, I would carefully try to pry out the cover from the hole through the front first- another option is use something like strong duct tape over the button to try to pull it out.

Z controllers use the exact same buttons

I don't know what you consider simple. The entire top of the case can be removed using a torx bit  (I think a 25) to remove the several screws on the bottom of the unit. Also, move the handles to the rear or near max position before attempting to lift the top cover. At that point, be careful because the throttle pot wires along with the wide ribbon cable attach to the front logic panel board.

Again, I would say, attempt to pry or otherwise pull the button and cover out the front without opening the case. If you have to, then opening the case is possible. Also, more important is when putting it back together ensuring the wires are all plugged in correctly and the ribbon cable does not get pinched or a screw driven through it when putting the case back together.

MTH parts search for "Z4000" or specifically the button, I had to search for "button". https://www.mthpartsandsales.com/shop/search/results

I move this to the correct MTH forum since the topic is not about a traditionally sized product and is focused on an MTH product.

Is the button stuck or does it still click?  If the latter, there is a capacitor across the terminals of the button, that when shorted, mimics a button that is held down.

Wow.  Not being good at anything electronic I think I'll have someone else do this for me.  I thank you all for your replies

I can’t find the thread, but recently, there were posts about stuck buttons on a Cab1, and a spray was recommended. Maybe someone can jump in with the name of the spray. I would try a spritz of CRC contact cleaner, but that’s not the product mentioned in the other thread.

Nick,

I also have a Z4000 and had a stuck bell button. I spayed a little "corrosion block" around the button and lifted and tilted Z4000 then started repeat pressing of button and it freed up. Afterward a little more spray and more pressing exercise loosened it up even more. We used this stuff on all our electrical equipment on the Bering Sea boats, swear by it, On Amazon it is

H&M CB4 Corrosion Block, 4-Ounce

Kevin

I tried spraying electrical contact cleaner in and it didn't loosen it up.    I'll see if I can find the H&M.. Thank you all.

I got it working.  I used Vernon Barry's suggestion and pulled it back in place with needle nose pliers.  One light tug and it popped back where it should be, loaded it up with electrical contact cleaner as best I could through the little gaps around it and all is well.  It felt like it was on something sticky in there but whatever it was it's free now.  I want to thank all of you for the various remedies. I used Vernon's because it was the only one I was capable of trying.  Great forum.

Just glad you got it working and it was simple. That's the best scenario we could hope for.

Have fun running trains.