Even tho it is relatively new, replace the leveling adjustment and see if the problem goes away. There is a non-replaceable spring in that adjustment that breaks. When it breaks, you dont get stable leveling and you may be drifting below the floor and not getting back due to a broken spring.

On second thought, the spring that occasionally breaks may be in the bypass adjustment. When you pull it out, there is a stem sticking out the back that you can turn, but it doesnt unscrew or screw in. This is where the spring resides. In the previous post, I meant to say, the up-leveling adjustment.

seen this same problem before, car runs fine for up to a month, then LOS. this was going on for 6 months or so, driving the route guy crazy. I came to troubleshoot the car, i would watch the car run all day, not a hiccup. I did not believe it was the valve, so started to change various parts, disable some etc. finally changed out the main cpu board. still the problem persisted. finally ran out of things to change so we replaced the valve and the problem went away. I would have bet the house that the valve was not the problem, as i could run it all day and never see a valve problem. I would have lost. replace the valve

i have been off for a few days i will see if anything has come up after the PSB swap, i will keep posted

All this valve talk reminds me of a time years ago when I was chasing the MLT on an MCE unit with a UC4...all new stuff. Maybe a year later after running fine, this MLT stuff starts to occur. After several adjustments here, there, and days going by before it would happen again, I finally found the L/S leveling adjustment screws loose with the dot on the stem to the S side of the line. DANG IT! No wonder it wouldn't hold an adjustment on LU. Scooted that dot back to the line, tightened 'er up and bingo! Sometimes ya just- get- bit.

set your los parameter to all zero's

that will disable los imput

derick i know i can disable it but the way the have the wiring for the new code i would have no protection.
so far no call back after the PSB swap