Where to start with fuse problem, (no turn signals/convertible motors)???

Get a shop manual, Chiton or Haynes and figure out what is on that circuit. Then disconnect 1 item at a time to eliminate that item as the possible source of the short. You problem is intermittent, so think about what electrical item you were using when that item quit working. That's where the problem is located. It could be a wire rubbed bare on sharp metal, a convertible top item, or a bad lamp socket. You get to chase it down - not fun with something that is intermittent.