>>1399719buy a headset spanner
they look like this
should only be a few bucks online or at a shop
you just need that, and a big adjustable spanner to work on a headset
headsets are really simply
you just take out your stem, open it all up, clean everything really well with rags and solvent if you need it and then repack with new grease (a tub of wheel bearing grease from an autoparts store is fine, and cheap).
If the races or bearings are pitted you should probably replace but you can likely get it useable, just notchy, with new grease still.
replacing it is probably a job for a shop as the cups need to be pressed in, but you can ghetto the tools needed. Threaded (1" atleast) headsets are not uncommon or expensive either. But try and service it.
