Originally Posted by
jbranting
Sounds like the Hi/Low pulleys, pull the cover and see if the disengaged pulley is making contact with the belt while running, may have to cycle the RPMs between hi and low gears in MDI a few times to recreate it, you'll probably see it visually as a slow retracting cylinder causing a bounce with that pulley, I've had it happen many times on my two fadals, A lot of the time you can take a 3/8 wrench and adjust the threads on the end of the cylinder where it threads into the idler pulley arm to where it makes less contact without making the belt too loose, I would check your hydraulic fluid level, just go through the top off instructions in the manual, but I would also anticipate replacing one or both cylinders sometime in the near future, adjusting them buys time but its probably starting to fail, if you get to that point and that doesn't fix it, it may be the hydraulic actuator, though I've found the cylinders more likely to fail. You may also want to check to make sure the magnets on those arms are making connection to the hall effect sensors, in enter next command type DI then hit enter, the DS and it will show the switches, use a dry erase marker to circle the hi and low sensor inputs then go to MDI and type S.1 and S.2 to shift back and forth, if its slow to read them it could either be from said failing cylinder or could also just be chips accumulated on the magnets. to make the inputs go away go back to enter next command, type DI and hit enter, the type X and hit enter. Good luck