Genie Powermax 1200 installed but only move approx 6 inches at a time.

https://www.teknuw.com/genie-pro-stealth-max-garage-door-opener-manual/

You have to match the unit with the correct accessories or those that are compatible with unit for it to work.

possible installation problems
call for a technician to check the fault

No rail wont fit quite right. I would consider a liftmaster/craftsman/chaimberlain with yellow antenna wire. The liftmaster models are 8355 or 8550. Not sure how those model #'s translate to the craftsmans and chaimberlains. These units use 3 frequencies which are chosen automatically by opener radio. This gives you the best option to avoid interference. Genie typalically uses 2, but their fixed, so its a crapshoot to avoid interference. Do not confuse these frequencies with the rolling code feature which is a static frequency with only the "channels" changing.

I have the Genie 3000 which is a 20 gal. wet/dry vac with a 3.0 HP motor. I had bought at Home Depot some 20+ years ago. I bought a replacement filter at HD made by someone other than Genie and claiming to fit my model...but it did not fit...too loose to stay in place. I did track down some hypo filters that might fit...but at $28+ for the filter I decided it was time to get a new model with better and cheaper and available filters. I bought a Ridgid WD1451 14 gal with 6.0 HP. It is so much nicer and quieter. HD regularly carries the WD1450 for $99 or so. The WD1451 is the same model but also had the car vac hose and attachments (a $40 set) included for free. That was a limited offer probably no longer available. Get you a new one and enjoy it...I did...and I still have the Genie...but I think I'll toss it because it is too big, too loud, and I love this new Ridgid.

Ckeck for codes

Change the sensor and make sure the magnet comes close enough to activate it. Sometimes I have even changed the magnetic ones for real switches too.

Never could get mine to work...turns out this model only works with Genie garage door openers manufactured in certain years, and mine wasn't one of those years. Bought a GIT model from a Genie garage door installer, and no more problems!

Either the coil/HEI module is bad or your on/off switch(kill switch) is bad. Check those first.

if the recovery discs wont work you may want to low level format (powermax) and try a fresh install. only downside is u will need a copy of windows with the serial key and u will lose all your data - http://digilander.libero.it/YorkOne/powermax/ - download and burn to cd >>> powermax-4.09.iso