Son-in-law's brother has a HRU216. When you engage the SP drive it drives inconsistently, and "clunks"!
Is this a common thing? It has done a fair bit of work, and he's not renowned for his maintenance skills

Could it be worthwhile making him a ridiculously low offer and repairing it?
Are parts available, & what sort of cost for a kit to rebuild the drive system?
Thanks in advance
