This was an unusual request and not the typical call out i get (usually caravanners dont bother fixing these things), this had failed because the software could no longer locate the satellite due to it requiring a firmware update, something i only found out after sorting the mechanical issue caused by the out of date software.
I had to re fit the toothed rubber drive belt and update the software for the customer.
Luckily the information was available on the internet after a little searching. The customer had no idea about the software update requirement and just let the dish rotate back and forth until the belt came off.
All was well when i drove away.