Hello,

Found this when searching for the same problem with my ST170, not sure if this will help but I have two options for my issue.

Wire brush the oil sump and spray with Lithium grease (my sump isn't leaking that badly) and see how it gets on.

If that doesn't stop the problem, then I'll buy a replacement from eBay and replace myself - at least a two hour job as garage I trust and use regularly told it it would cost around £350 for parts and labour.