Hello, I bought a kity 637 yesterday with the thicknesses jammed solid at its lowest point the planer works fine but the thicknesses won’t budge took the sides off today and under Neath the four sprockets with chain on seem jammed but is it the four bolts that go up and down that is jammed I don’t know or is it something else. I have smothered everything in penetrating oil, while I assess it. Any ideas or help would be appreciated. Thank you