Small Engine Troubleshooting Problems? Ask a Mechanic Now.
Purging Air from Hydrostate Oil Circuit 1. Check oil level. 2. Place vehicle’s drive axle on jack stands with wheels off floor. 3. Start engine and operate at low idle. 4. Repeat opening and closing of bypass valve while alternately depressing forward and reverse pedals. 5. When vehicle starts to move, increase engine speed to high idle. 6. Repeat quick starts and panic stops until transaxle gives full response. 7. Recheck and top-off oil level
Here is manual for K61, I has same system,page 36.