Upgrading the AS2518-18 / -49 rectifier board

Steps

Replace every .156" header pin (resoldering also cures cracked joints) and fit Trifurcon pins in the housings; sanding old pins is only temporary.
On the solder side, jumper J1 pin 5 to J3 pin 10 (plated holes make this easy) to add GI copper.
On the solder side, jumper J1 pin 6 to J3 pin 9, soldering to the header pin and trace, to add 43 V copper.
Optionally drill a 5/64" hole left of J1 (and on the -18 one near J3) for the next wires.
Scrape the solder mask off the big ground trace next to the headers and solder a wire from it to J1-1/J1-2 (GI ground); on the -18 add a second wire from it to J3 pins 1-4 (lamp driver ground).
Desolder the old bridges from under the board.
Fit 25 A 200 V (or better) wire-lead bridges on top of the board, middle one first, "+" (notched) lead at the top, at least 1/2" above the board, dog-legging the leads; cases may touch.
Bolt a heat sink to each bridge with heat sink compound before soldering (BR1 must have one), then solder each lead on both sides.
Replace CR1-CR4 with 1N4007, bands the same way as before.
Check R2 (25 ohm); replace it if outside 23-27 ohms.
Check the fuse values, then refit the board; the old bridge screws and heat sink plate are no longer needed.

Line voltage (120 V AC) is present on the rectifier board and its J2 connector; unplug the game before touching it.

Source: Repairing Bally Electronic Pinball Games from 1977 to 1985, Part One, Clay Harrell (pinrepair.com)