DEC H7140 (11/40) power supply revisions and general advice?

Hey all -- Once again, I find myself in over my head debugging a power supply, this time an H7140 from a PDP-11/44. Here's the skinny: I examined the supply physically before experimenting and found a capacitor on the Bias/Interface board that was leaking, bursting and rather burned-out looking (not a great sign) -- this is capacitor C4 in the printsets on Bitsavers (http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/pdp11/1144/MP00897_11X…) Everything else looked OK physically; I replaced the obviously bad capacitor at C4. When power is applied (plugged in, breaker switch flipped to "On") the relay does not click - based on my readings of the manuals this should happen after the bias voltages are up to spec. I measure 308VDC on the lugs on the top of the memory board, so that's at least something working. Getting to other points to test voltages is a bit more difficult, especially with those high voltages in the way, what a nice design :). Switching the front panel switch to "Local" (or any other position) has no effect -- no fans, no LEDs, nothing. I've double-checked all the wiring and everything looks OK. Capacitor C4 looks to be involved with the START-UP DRIVE signal circuitry (which drives the relay) so the behavior I'm seeing makes sense if C4 died and took a couple of things with it (or if something else died and took C4 with it). Here's where it gets kind of odd -- I spent some time testing diodes and transistors in the related area near C4 and while doing so I noticed that there are four diodes (D1-D4) listed on the schematic that are missing from my board. "Missing" as in someone clipped them out at some point -- there are just nubs of the leads left. I'm not sure why this would have been done, but there were a number of ECOs applied to this board (a few wires and resistors added) and I don't want to assume that if I just put four new diodes in that it won't cause other problems. Anyone know if there were other revision levels of the bias/interface board that would have done away with these diodes? Anyone have an H7140 they can easily crack open to compare? (It's actually relatively easy to get to, if you can get to the supply...) Thanks as always, Josh