Making solid filler bars is not too difficult. I used 1_8" thick steel stock 1 1_2" wide. I first tried 3_16" thick but that thickness reduces the effectiveness of the concave bars. I attached 5_16" carriage bolts to the filler bars in 3 places (center and near the ends) through holes Id squared with a file, with 5_16" nuts which will clear between the concave wires. Then I made square washers from 1_4" stock which were backed by lock-washers and 5_16" nuts to hold the filler bars in place on the concave. You remove the two inserts from the front of the grain pan to get at the bottom of the concave. I cant imagine how youd get at stuff in a hydrostatic combine. Getting the filler bars into position can be a real pain, especially if youre filling all the slots for combining clover. I made up a bracket to mount magnets on to the cylinder spider to which I attached the filler bars, which I would then rotate into position. Once in position, I used a 1_2" aluminum rod, 5_16" tapped at the end, to engage the filler bar bolts through the concave wires, and pulled the filler bars down off the magnets into position. Its a very dirty dusty job, even with a full face respirator (I use a 3M Airstream helmet),as you have to get all the chaff and straw out of the way before the filler bars will get right into position.