Sounds like a coil / coil diode is measuring a short. With a multimeter, test each coil and anything that measure under 2 ohms is seen as dead short which will blow the fuse. Check that you are also replacing the exact same fuse value - I think they are 1.5 ohms slo blo - check the schematics on the wiring page.

Front door looks like a coincidence. Get rid of the button and set the game up to give first credit at 10,000 points - you will never need to open the door again (except to look at it) 

Thanks Nino,

I'll test the coil diodes as suggested.
The button will stay though, I love the call outs when adding credits on these old Bally's. I get great entertainment out of Synchronising credits between Fathom and Xenon. Small things amuse small minds I know but I still find it funny.