I am looking for some insight to a problem I am having on my 78 k5 Blazer , I have a speedometer ratio adapter to adjust for my tire size and I have stripped two of the adapter shafts, I have cleaned the speedometer cables and lubed with graphite, and it still happens I am wondering if maybe my cruise control box is binding to cause this or if my speedometer head is causing this I would appreciate any input form anyone who may have advice. Thank you