Have a 2011 FLHTK 18 months after purchasing it new the heated grips started acting up then completely quit working. HD replaced/repaired them no problem. Now about 24 months later there doing the same thing. sometimes feel like there not working at all at other times feel like there working about half way. Do these things have a working life of about 2 years. Any suggestions on where to start trouble shooting , or possibly a video of how to tear into this project. How difficult is it to replace myself if I decide to take on this project myself.