How do I fix "sticky" or "floating" shafts on my loom?

Check to make sure that the loom is level. To check level, place a level across the front beam and then the back beam. If the loom is not level, you can place a wood shim or rubber level (found at hardware stores) under one of the legs. You can also try turning your loom 90 degrees to see if your floor is level in this direction.
Try spraying a little bit of silicone spray in the metal track. Do not use WD40—it eats at the wood’s finish. Do not use wax in the channels—it will get sticky and build up in the tracks and add to the problem. You can use hard paste wax on the harnesses, but it is important to buff it well to remove any residue that will become gummy.
Make sure the tie-ups aren’t in a position that pulls one lamm under another while treadling. Tie-up cords should hang straight down to the treadle.
Make sure the brake ratchet dog is in place. It can flip backwards and catch under the first harness.
In humid climates, it is possible for wood to swell. Try loosening the jack retainer bolts a half turn to allow more space.

Make sure the jack and lamm is attached to the harness. There should be a screw and lock nut holding it in place. If the lock nut is too tight, use a little silicon spray to loosen it.
Make sure the metal supports of the jacks aren’t bent. This could cause a wooden lamm to be out of alignment and catch on the one next to it.
Check to make sure all of the pins are pushed in all the way. If any are loose, the jack and lamm could catch on an adjacent one. If you need more pins, you can order new ones.

Make sure heddles are spread evenly. If there are many more heddles on one side, this could cause the side of the harness to drop and make the harness stick.
Make sure heddle bars are locked in place by the heddle bar hooks. Check that the ends of the heddle bars are in the grooves in each side of the harness.

Check the sides of the harnesses for scratch marks. If there are any marks, check the metal tracks to make sure that the screws are tight and flush with or below the surface of the metal.
Check to see if the harness is swollen or warped. Take the harness out and lay it on a flat surface to see if it is warped.
Does the harness have any movement in the track? It should have some play, but not too much. Try the harness in different tracks.
Too much movement can allow a harness to tip toward one side. To correct this problem, cut a strip (7/16″ x 13″) of thick paper such as a file folder, to fit in the harness channel. Slide the strip of paper into either side channel of the harness that is sticking. This will reduce the space where the harness can tip. You may need one or two strips of paper. You can also purchase harness shims on this website.