I've been looking at the picture for sometime, and only see the too long bolts on the one intput connector as you did, someone changed that along the line...
The amp is reasonably classic in design, as most of these are buildt in the same configuration, with or without bias or class C or class AB1.
This one has the bias, so clearly an classs AB1 for SSB
It has an rudimentary Pi filter, so it will be relative clean if it is not overdriven.
Looking at the resistor network for selecting the drivelevel, i see no burnt resistors there, just check if they still have the value as read out from the coloured rings.
2SC2879, 120 watt output with 7watt input gain 15 dB at 30 mHz
You should see with adequate drive 200 watts output with an carrier of 12 to 20 watts bypassing the resistor network.
If both transistors are good, but the amp doesn't have the output it should have, but does pull the amperage you have an faulty C or an fault in the output circuit.
In there the HF
partly goes to mass through an faulty leaky C or other faulty component.
Without physically putting it on my testbench, you need to check the components.
The amp looks clean, no ugly repairs or "mods" i can see in the picture.
So mostly an component failed, relais has burned contacts, or bad solderjoint.
Make sure the in and output connector make good ground.
Rebuilding my KL500 to amateur use amp, the extra grounding straps there gave an almost 3 dB gain.
Sometimes the in/output transformers are at fault.
The copper tubing through the ferrites must be thoroughly soldered to the pcb wich is then soldered to the collectors and output or basis and input.
The (teflon) wire through the transformer should not make contact with the tubing, check for nicks in the isolation there.
Looks like an decent little amp, hope you get it sorted.
The network from collector back to the basis , C, R and the L form an feedback from collector to basis depressing too much gain, and stabilising the amp.
Checking the transistors is relative simpel, lift the basis flaps from each transistor, use an multimeter in diode measurement and seee if the transistors have about 600 Ohms in one direction, basis to Collector, basis to emittor, and thee other way round it should be almost infinite resistance.
If you have that, the transistors are good, and the problem is elsewhere.