Looking at the wiring diagram, first thought would be to change the fuel level sensor (LPG) which is directly fed from FU5. Swop to another machine if available? If that doesn't cure it then its most likely a wiring issue, maybe a wire rubbed through & grounding on the chassis somewhere. I would think an internal fault on Access 1 causing a 10A fuse to blow intermittently is very unlikely.

One suggestion is to replace FU5 with a mini-blade 5A auto-reset circuit breaker, this will reset when the fault clears and allow the customer to restart and continue using the machine until eventually the fault becomes more permanent. Not great but maybe better than constant visits.