The first thing I would do it inform the owner and describe what is involved fixing it!!
He might not be aware of the problem or want to fix it, or worse, think you are baiting him into a big repair bill.
Depending how well you know him, I'd get the parts money up front!
BTDT,
snooker me once, shame on them, snooker me twice, shame on me.
When money is involved, relatives snooker you first, them "friends" second, ---
then strangers.
Advice from the skool of hard knox.
