My mower starts and seems to be running fine but the motor will shut off after the blades start spinning. Sometimes they will spin for about 10 seconds before the mower dies and other times it's immediate. Everything looks good with the seat safety switch and the PTO seems to be engaging because the blades start spinning. If I spin the blades manually with the mower off they spin reasonably free but there does seem to be some squeaking and resistance. Everything was running good when i put it away for the winter. Any suggestions would be greatly appreciated