Lab Series L5 Compressor Not Working

[Questorz]

I have a L5 all original that the compressor doesn't seem to function on. When I turn on the amp the compressor lamp lights for a few seconds and then goes off (whether compressor switch is on or off). If I turn the compressor switch on plugged into the second channel the LED does not light in any position of it's controls or playing through it. The sound changes none at all, no clicks, noise,  compressor effects, etc.. I haven't dropped the chassis and checked the switch or other components. I have played the amp for extended time periods and the power seems fine in channel 1&2 and it's quiet as a mouse and sounds good. Reverb works fine. I plugged up a Zoom 5050 chorus through the effects loop and it works perfectly. The frequency pot doesn't seem to change anything that I can tell. I haven't been able to find a users manual online so I'm not sure if I'm doing something wrong. This unit looks almost mint with original speakers and cover. Any quick suggestions or a manual that someone could send me would be cool. I have all the schematics and notes but don't see anything about the compressor not working at all unless I missed it.

[teemuk]

The frequency pot changes the center frequency the mid-range control works on, naturally these tone controls only work on the 2nd channel. The tone controls on the 2nd channel are active type: They can cut and boost and in the 12 o'clock position their response is entirely flat. So, turn the mid-range to its either maximum setting and play something trough your guitar while turning the frequency knob and you should hear it affecting the mid-range clearly. If not, the circuit is broken.

Can't really help with the compressor other than that based on your description it seems to have failed. I recall those had the compressor control operating somewhat backwards where turning the control counterclockwise actually resulted into more compression (I could remember wrong though) but if the LED doesn't indicate peaks in any setting then its safe to say the circuit is busted and you need to start measuring what has gone wrong.

Never seen a manual for these but I bet the schematic practically tells more than a manual would, assuming one can read the diagrams.