Milltronics partner 1 dead spindle drive

Hi, this is my first post here and I though I'd share my ongoing attempts to fix my machine.

Maybe if I successfully fix it this will help someone else, and maybe someone can help me if I'm on the wrong track with my attempts.

I bought a non-functioning 1995 series H partner 1 mill with centurion V control last July, hoping I could fix it and end up with a working mill for cheap. This mill had some major updates around 2012. The control is running on a board with a compactflash card, and the servos and spindle motor are Custom Servo Motors. When I got it home, I discovered that it was wired with a single phase nema 14-30 twistlock plug where L1 and L2 were connected to the hots, and l3 was connected to neutral. The control powered up, but it wouldn't home, and none of the axes would move. That made sense to me, with the control having a 110/220v pc power supply. The seller told me it never worked since he got it, so I suspect the owner before him had wired a three phase outlet with a single phase nema 14-30 receptacle, and as soon as he plugged it into a single phase outlet L3 was shorted to ground at the panel, and it blew fuses. I hooked the machine up to a proper three phase plug, replaced 4 blown fuses, and it fired up. Everything seemed to work fine, I was happy, and I got distracted with other projects until a week ago.

When I fired up the machine, I homed it, went to MDI, and entered m3s500, enter, and pressed cycle start. Nothing happened. No alarm, no estop. It was working fine when I left it over the summer. I noticed that none of the leds on the spindle drive were on, and nothing happened when I pressed it's reset button. I confirmed it was getting power, and I took it out in hope of finding something easy to fix like a blown fuse. No such luck, but I did notice an area that looked like a component may have let out the magic smoke. It's not obvious which component may have failed. This spindle drive is an MPA-50-mill, and I am seeing refurbished units on ebay for around $2800. That's not in the budget for fixing this machine.

I have since cleaned up the board, replaced every component that looked like it may have been the issue, and a mosfet on the back side of the board (near the nut near the blue transformer) on the advice of my dad, who knows far more about electronics than I do. I put everything back together, fired up the mill... and same problem. I took everything back apart again, looking to see if I had re-fried any of the replaced components. Nothing was obviously wrong and I spent the better part of an afternoon staring at this thing, poking around with a multimeter as if I know what I'm doing... and I finally notice what I had assumed was a capacitor was labeled with an F2 on the board, and when I look under magnification, I can just make out "BUSS 1A". And it's blown. I've ordered some equivalent fuses and I'm hoping that after I get this replaced that it will work.

-Nate