Motor Coach closed for good in March i believe. Haulmark as a brand sold to some larger trailer manufacturing outfit so now when you go to the web site it's all trailer. I called the number and was told they can't help with any Coach needs. I'm very happy with this RV and will probably have it long term, but I can't find the slide controller(s)
For the longest time Haulmark was part of Wells Cargo trailer. We looked at them but ended up with NRC as they would build what we wanted.
I don't know for sure but phone Jerry at NRCMods (Middlebury) and see if he can help you.
As mentioned previously, look for a toggle switch. Start flipping all the switches and see what moves. I had the same problem with an "Elite" brand RV. Turns out it was not built by Elite and have no idea who built it. No documentation in it anywhere. Took weeks to figure out the electrical stuff. Flip switches and you will eventually find it.
If you are looking for the switches the one for the living room is mounted on the wall between the fridge and the shower (there is another momentary on/off switch on this wall as well and that is the battery boost button to start the generator if your coach batteries are dead)and the one for bedroom slide is mounted on the wall between the bathroom sink and the window at the foot of the bed.