NFB Loop switch - Good idea
Slope resistor toggle switch - I wouldn't. You're messing with DC plate voltage.
Half power switch - IMO, not worth it. On a 50W all you can do is switch from Pentode to Triode mode. Doesn't lower volume appreciably and messes with tone. Get to know the Master Volume or get a C-Lator

The relays I've got have a wiring diagram on the top. The coil is the rectangle symbol that's connected between pin 1 and pin 16. Another way; turn the relay upside down. You will notice that the pins are not symmetrical (2 rows of three pins spaced close and at the other end two pins spaced much farther away). The isolated pair of pins is the coil and it is inserted in the socket with that end oriented toward the filter cap board.

For 120V operation tie the BLK/YEL and BLK together and solder to the neutral terminal of the power supply socket. Tie the RED/YEL and RED together and solder to the Mains switch. The 6V leads get soldered to the relay power supply board. No difference which gets soldered where.

I guess I'm a little further ahead than some. I didn't file the holes as Nik recommended but after installing all the hardware on both front and back it dawned on me that it might have been a good idea. So I checked continuity to ground from the backs and shafts of all pots and shafts of the switches. All good. The pot holes were actually kind of tight so I needed to spin the pot to get it in all the way. Guess that took care of whatever coating was in the hole.

Right. No change there.

I only build OTS style amps.

Hey Captain,

Just an FYI.
I just received my latest kits and the chassis are now powdercoated steel. Kind of light tan gloss finish. You might want to wait until you receive it to decide what you want to do.

I can give you some hints at making those face plates your own too. PM if you are interested.

Changed out the cap and it all sounds good. Thanks for the help.

Update
Swapped out the tube for a Raytheon BP (Probably a waste of a good vintage tube) but it sounds much better. Might just replace the cap anyway.

I got to check it out tonight and there is quite a bit of noise when using it. Coming out of the recovery stage. Noise varies with pot position and the bright switch actually reduces the noise. So I'll probably change out the cap.

The reason I posted was that I couldn't get a good measurement of the capacitance. But my DMM sometimes gives strange results especially in the higher uf range. I have since powered it up and all voltages agree with those in the voltage chart. I'll be playing through it tonight. I guess that will be the ultimate test.

Thanks again

I was checking out my C-Lator build the other day starting with basic voltage measurments like filament voltage, etc. Connected alligator clips of my DMM to pins 4-5, 9 and while measuring I think the clip on pin 9 might have slouched over and briefly touched pin 8 (47uf electorlytic cap). Could I have fried the cap with that AC voltage?
Thanks

I've used them on four builds so far and am very satisfied,

If you mean using the 5 volt tap for the relay power supply, it worked for me. I used a Magnetic Components 40-18029 for my 50W FM. The relays pick up at about 8.5-9.0 volts. Using the 5 Volt tap I measured the relay coil voltage at about 11.5-12.0 Volts.

I don't know about you but I'd want a backer board for the Bias/Rectifier board. You have close to 700 VAC entering that board from the PT and 450 VDC or more heading over to the filter board. Using standoffs it is possible (although remote) that some conducting material could get between the underside of the board and the chassis and short something to ground. With a backer you pretty much have eliminated that. I've built five of these type amps from Nik and received backers for all boards except the internal tone stack board that comes with the HRM. I just went to the Depot and bought some appropriate size rubber washers and used them as standoffs.