Some 40 yrs ago when I first started working on machines I went & oiled a neighbors old treadle machine,it got stiff I oiled it more & it tied up.She wasn't happy so I took the head to work & told an old timer what happened & he started laughing & finally after a few minutes he told me yes,that happens from 3 in 1 oil.It has wax in it & it builds up after time & when you use regular machine oil it swells up in the bearings.So I put some diesel fuel in the top shaft bearings ,it started to turn alittle & took it home & held the wheel against an air compresser belt & it freed up.She was happy when I brought it back.