There are two 6 mm threaded holes at the front of the steering head, there should be a plastic plug in each of the holes .
If they are not there, water can get into the bearings, usually the lower one gets damaged .
I put grease fittings in these holes and grease the bearings every few years .
It makes quite a mess doing it !!
You need a lenght of threaed rod, large diameter drilled rubber grommets, large area washers and two nuts .
This tool goes through the top nut on the steering head, with another grommet and large area washer on the bottom to contain the grease .
If I can locate the tool I'll post a picture of it .
