Manual Shift From OD or D to 1 at 55 MPH - Shifts at 45 MPH

MANUAL SHIFT FROM OD OR D TO 1 AT 55 MPH - SHIFTS AT 45 MPH
1. Main control pressure malfunction.
2. Sticking or dirty valve body.
3. Governor damaged or worn.
4. Improperly adjusted or sticking kickdown linkage.