Kenmore 600 series washer

I have an 8 year old Kenmore 600 washer (model # 110229622800) that will not spin during the normal cycle. Makes a humming noise like it is trying to spin but doesn’t. It will fill with water, agitate, drain, rinse and drain again but neither spin cycle will work (after the wash nor after the rinse cycle). For a while, I was able to move the setting knob manually to spin and get it to run but not any more. I replaced the motor coupler and checked the clutch assembly which seems okay. Checked the continuity on the lid switch with a multimeter and got a signal but am going to try to replace that too. Trying to fix myself but not sure whether to spend money on a timer if I’m not sure exactly what the problem is. HELP! Any suggestions?