Not sure if anyone will be too interested since no one has posted to this topic in a couple years, but I find it valuable when such issues are documented to completion. I've scanned about half the threads here and found a couple similar situation.

Anyhoo, I have an LFM-1. Not sure when I got it. I think I bought it around 2002. I've been gradually updating components (big Vizio LCD, Outlaw 975 processor) and finally completed a modern system last week when my Outlaw 7075 amp arrived. When running the 975 speaker test signals, I discovered that my LFM-1 had quit working at some point since it was last confirmed working earlier this year (when I got the LCD Soundsystem 'Shut Up And Play The Hits' blueray).

I will be contacting Outlaw once they are open this week (or are they on vacation?), but this component is long out of warranty and production. I understand they may not be able to help.

The symptoms:
No sound or only very faint sound from LFM1. Power cord checked. Red LED when switched to "off". Green LED when switched to "auto" or "on". Starting with volume knob down an then turning gradually to max, I get the similar symptoms no matter what crossover or crossover bypass setting is selected. Just a faint sound at max volume.

Of course I confirmed the power cable, main power switch, and fuse. As per the user manual's trouble shooting instructions, I removed the driver to confirm the internal cables were still connected to the driver.

The test signal is good. I switched the RCA output to another speaker to verify.

I will test the driver by connecting directly to an amp with a test signal.

I can't think of any other steps to take, besides take it to my dad, a retired electrical engineer, who has helped me troubleshoot repair powered speakers and my 1981 Atari Tempest machine.

My suspicion is a failed power supply board, which I've experienced with two studio monitors with the same symptoms. Also I see one discussion thread here that sounded similar and the conclusion was a replaced power supply board.

My concern is that Outlaw may no longer have replacement parts, and the cabinet and driver may not be compatible with boards from the LFM-1 Plus, EX, or X12.

I expect Outlaw will be able to help you with further troubleshooting and any needed parts. They can at least provide you with the specs for any parts you can get locally. Shipping it back to them may be cheaper than buying a new sub. It could be the amp has gone bad. I would check the input cable also.

I did confirm the RCA cable is good, and I connected the driver directly to my amp's stereo right cable to confirm the driver is functioning.

I'm shipping the back panel to Outlaw for repair. The responded to my support request first thing this morning. It sounds like it won't be a problem for them, and they estimate $75 plus shipping. I was hopeful the sub could be retrofitted with updated boards from more recent models, but Outlaw says that's not feasible. Oh well. I'm happy with the LFM-1 and at 80 bucks it's a no-brainer repair.