I just changed my mower belt on my john deere 135. When I went to re-engage the mower, the belt engages and the blades spin at a low speed -- and I don't hear the mower engine kick in like I did before. When I went to trouble shooting at John Deere site, these items are listed as reasons why mower deck doesn't engage. Any suggestion? Mower deck drive belt slipping or broken. キ Mower deck belt tension spring not installed or broken. キ PTO switch faulty. キ Operator presence switch not engaged or is faulty. キ Fuse is blown. キ Loose electrical connections.