Those smaller DMD's are pricey. I've been lucky that my TMNT DMD has always been rock solid.
I'm not aware of any game specific mods for this game. It sounds like a lot has now gone into it already. Maybe getting it powder-coated, if you like that sort of thing.
My TMNT is a keeper for me, I did something similar to it a year or so ago that your doing to your machine now, I even had all the trim powder-coated to match the wire-form ramps.