Hey everyone! Need a spot of help figuring out what's going on with a friends Paragon.
The back story, a GPE rectifier board and Altek MPU were in this game and it worked properly for two years. No work was done to it, and it was not moved recently.
One day one of his kids turned it on and it just didn't boot.

The only problem's I found were TP3 the 12v was only putting out 10.2v and the MPU and Solenoid Driver were only getting 4.1-ish volts, and R1 was hot, like almost dangerously hot (I know resistors get hot, but this one was almost hot enough to actually burn you)
I was getting flaky readings on BR2 so I replaced it with a higher voltage rectifier with the same amperage (600v-35amp). Plugged everything back in and still got only 10.2c at TP3.

Like a dummy I forgot to check the resistance of R1 while I was there, but since it deals with the 48v I kind of figured it was not directly tied to this problem.

So, where should I go from here?

* ok, so I just read that this resistor may get up to 200 degrees F on the GPE schematics so never mind that...

Thanks Quench I'll see if the owner can trace that out and report back ASAP.

Sorry for the delay, tested J3-p10 to J3-p17 and got a good tone. The connectors all look good, and the cap was replaced last year. I'm waiting to see if he can test the cap in circuit to get a rough idea if it is failing with his DMM while I wait for my new ESR meter to arrive.
I'm still concerned that the 12 volts form the rectifier board is only outputting 10.02 volts and were only getting 4.2 volts from the regulator. He has a replacement regulator, but I don't want to mess with that unless absolutely necessary.
Thanks!

Thanks Quench this is a lot of great information. If I remember correctly I did measure TP3 on the rectifier board with J3 disconnected and it was still 10 something volts (I'm not 100% sure what it was, it was similar to the connected 10.2 volts, but not exactly the same, may have been 10.5or7 volts)
Unless you think I should go a different route I'll replace the cap and possibly reinforce the ground return as recommend in your earlier post.

It is probably going to take me a while to get back to his place as my real job is getting busy for the holiday season, and he lives about 60 miles from me (which in Texas is almost next door), but I'll update as soon as I can.

This is why I think the cap may be failed/failing it's a 25v 11,000uf cap, but is really small. I'll report back after I get my hands back on the game. Thanks again for all the help.

Success. I got the board from the owner replaced c23 with a 35v 15000 uf cap (I know it's a bit higher rated than spec, but I've seen them used on this board before). I also tied the grounds together as suggested earlier.
I used my Spy Hunter to test the repair. Plugged the board in with the MPU disconnected and powered it up. I am now getting 5.12 volts. at both 5 volt test points (TP1&3)
Powered down and reconnected the MPU to test game boot and functionality. MPU boots, displays work, sound works, YAY! Start a game, flippers work, switches register, but I have no other coils working, BOO!
Swap in my board (which was working the last time I played it a few months ago) same result, no coils except flippers (well the knocker works and the coin door relay coil work).
Since both boards are acting the same way I'm assuming the the issue is somewhere else in the game. I'll get to that at some point soon.
Quench thank you.

Yup, totally blown. Somehow missed that fuse while I was checking every other fuse in the game.

Thanks again Quench. I'll mark this as solved.