On our paragon, the voltages test good on the transformer bridge rect board.

The mpu gets a quick flicker and the machine occasionally gets the 1 LED flash. Occasionally it also does not and anything from a solenoid firing to a sound board bong to nothing occurs with each power on/off cycle.

Is it likely that the original u1, U2 and u6 have become corrupted? Or is another scenario likely?

Yes, there was damage but it has since been repaired. I accidentally shorted f2 and f3 on the transformer board which I'm suspecting corrupted the original roms.

As an update, I swapped in a working mpu from a Star Trek and the machine booted consistently.

I then swapped in the following components (u1, U2, u6, u7, u8) from the ST board into the Paragon board and had the same incomplete boot. The Paragon board typically got through the first blink and the first two LED flashes.

As the u15 is not socketed, I could not swap that in. I plan on swapping in the PIA's and seeing if there is any change.

I have a Fluke 77III. I am not sure if/how to read frequency with it.

I was able to borrow a local friend's mpu from a Star Trek and found that U11 has failed on my board.