If you look back through former 'threads' you will see what people think about the various 'motor movers' on the market at the present time. The concensus seem to come out in favour of the Powrtouch. The no quibble guarantee (5 years from new)covers all parts (including the little pin on the isolating key). They are also a very pleasant company to deal with if you have any problems.
We have had other 'movers' fitted to former caravans but, I must admit, the Powrtouch mover is by far the best.
Truma guarantee their mover for 12 months, but now do an extended warranty but you have to pay extra for this.
Powrtouch also 'price match' so check around your area and see what a newly fitted mover of another make would cost. Then have a word with Powrtouch - I am sure you will be impressed by their service.
Good luck.
Ann