This is what my coin door looks like from the front (with one of the reject buttons removed):

And here it is from the back, showing the coin mech holder:

I need to replace the reject push button, but the ones available from Happ don't fit my mech holder. In the following pic, the original reject button is on the left, and the new Happ is on the right (no coin slot):

I see that additional Happ parts would be needed to complete the new reject button assembly (circled), specifically the coin slot:

But here's my problem... The new reject housing circled above has the mounting screws on the top and bottom, and my coin door and mech holder has the screws on the left/right of the opening. If I get a whole new mech holder, I will need to drill new holes in the coin door on the top/bottom of the opening.
And finally, the question... does anyone have any advice of what else I can do, short of getting an entirely new coin door?