I'm down by Cicero. No tank filter, I found one online. New one is $250!Where you located, I'm up around Plymouth type area.
If you look where hose hooks to tank and it only has a plastic nipple, then no tank filter. If it has a black rubber grommet on bottom, then it has a small screen type in tank filter. I don't remember which kohler engines had them , but alot had block mounted pulse fuel pumps on the side near the ohv cover
Just found a thread of a guy who reports a similar problem, same model of Deere. I think I am gonna try your trick in the AM...disconnect the line before the filter or even before shut off valve. If nothing comes out, then I will pull the tank. Found a video for that on YT, looks like a < 30 minute job. Will blow it out with air and flush anything into a pop bottle if needed.
Mrs. Miguel told me to stop messing around an buy a new one, but I would rather buy guns, ammo and reloading components than a new mower. Then again, Mrs. Miguel would prefer the new mower...
I'll post an update tomorrow. I'd start tonight but don't think the neighbors would appreciate it if I got it running tonight.