The internal mechanical components might have worn out or need lubrication.
The lens you linked to is autofocus,however the ones I were talking about are the older manual focus ones like the following:
http://www.ebay.co.uk/itm/NIKON-Micr...item3cbd8b2477
IIRC,the lens will work fine with your D70s. However,there is no metering and no autofocus
AFAIK. Funnily I use the 105MM lens via a simple adaptor with my Sony A200 and it meters in central weighted mode and I get focus confirmation. The lens is very sharp and it was even the case with my old Nikon film SLR.