Sole f63 treadmill LS1 low speed error

I have a Sole f63 that is about 8 years old in a home gym that is dust free and a pretty good environment for this equipment. It has just started to get an LS1 low speed error that I can't figure out. It will start up and run for about 7 seconds then get the error and stop. I have to turn it off and back on to get it to go again. I could see the flashing of the indicator on the control board coming from the speed sensor. I've inspected all connections and even examined the control board very closely. I sent the control board off to circuitboard doctor and they tested it on their treadmill and it worked fine for several hours with a person on the treadmill and without a person on the treadmill. They went through the whole board and upgraded whatever it was they recommended and retested and it worked fine on their treadmill. I reinstalled it on my treadmill and get the exact same LS1 error after about 7 seconds of running and it stops. I can power the motor with a 12 volt battery and it will run and run just fine. The belt tension has not changed and moves easily. I ordered a new speed sensor since the board tested good, to see if maybe it was bad even though it was sending a signal to the board. I have tried to adjust distance from the magnet on the wheel to speed sensor with no luck. I will lubricate tonight with silicone lubricant just because I think it's worth a try and should be done as preventive maintanace anyway. I am wondering now if it could be the upper control panel where the display is. Everything I have researched so far nobody has mentioned this as a possibility. Anybody have any ideas?