As this is the currently active thread on Metcal repair, I'll add a story here, even if it doesn't directly concern the RFG-30 but the MX-500p-21.
The unit in question was completely dead. Measurements indicated that the output transistor Q4 was shorted. After replacing the transistor, the station worked but died after a short time of use. After again replacing Q4, I measured the output stage supply voltage (across C8), which turned out to be way too high at around 40 V. The LM2576 regulator for the output stage was tested and confirmed to be operating correctly. The feedback signal to the LM2576 was at 1.23 V, hinting that the RF loop was in regulation, but that the output stage was delivering much less power than expected, causing the buck converter to compensate. The gate waveform of Q4 looked reasonable, if a little high (the driver stage voltage is derived from the buck converter output, so this was a symptom of the high buck output voltage) but drain waveform was a mess, with a significant oscillation at four times the 13.56 MHz operating frequency. I measured all the passives in the matching network, and all components measured within tolerance, except for C27 (130 pf silver mica) which measured 60 pF. I borrowed C27 from a second broken MX-500p-21, and measuring it before installing it showed that it was also out of tolerance at 45 pF. C28 (which is identical to C27 and connected directly in parallel) measured spot on in both units. Replacing C27 in the first unit with C28 from the second unit restored it to normal operation, with the output stage supply voltage within the normal range. It appears that the second unit had the same fault, so this might be a common problem. It is probably a good idea to measure C27 and C28 in MX-500s with blown output or driver stage transistors, and to replace both if any of them are out of tolerance.
Next up is a pair of MX-PS5000s with the same symptom; dead buck regulator. After replacing it, they work for a short time before the regulator fails again.