This fan has 4 wires and a black jumper wire. Wire colors are white, gray, brown, and purple. I have white wire to L gray to 1 brown to 2 purple to 3. What I get is 2 positions off and one is low speed the other is higher than normal high speed. Don't know where the black jumper goes. This fan is about 25 yrs old but ran well before the mount nut came loose and broke. I've used many different wire combinations with no success. Thinking I might try to buy a 3 speed and off single pole switch to substitute, although I've compared contacts with an ohmeter and all contacts compare the same.
Can use some help if available. Selling the house so I'm trying to get this fixed.

Looks like the black wire should most likely go to L. Try the following: Black - L, Grey - 1, Brown - 2, Purple - 3.