I bought a new key fob from a local locksmith for my 2003 C430 convertible. Works fine when car is warm but will not lock/unlock the car after car has been turned off for 5 minutes. Sometimes will lock itself after sitting for a longer period. Locksmith says I have bad vacuum tubes and/or a bad vacuum pump. I think it is a programming issue. Your thoughts? My email is totuttleca@aol.com