It seems that your motor is not tracking the arc perfectly. Achieving this takes a LOT of time and trial and error. If you are getting AMC 3 and IA 5, that means you are tracking the arc good general at higher elevations but when the motor starts moving far west and/or east it will not be on target and it will miss the satellite.
Galaxy 10R transponders are very weak especially for an 80cm dish. The strongest transponder on there is probably the volkswagen one and the research
channel one which is 11805 H I think.