OK, do you have a PM3-75LK and does it have an LED lamp?
If so you have three stage or single stage that adjusts with the pot.
Let me know what you have and I can find out more about it.
On the holes that are too small---on the prototype I had, I had to take the lid off to see what was there to understand what was going on with the switch and pot. I got mad at it and drilled way bigger holes in the lid's side so you can see what is there and what you are doing.
My feedback had a lot of notions of potential mounting problems for where it could go in an RV so you could get at the holes and see what you are doing. I like the external ADJ pot knob on the previous models way better, but even there you have to get at it. Works ok as a portable out in the open.