I didn't know how to make a link, but this is the URL to Turntable Basics. They have 10cc bottles of silicone cueing mechanism fluid, for replacement of broken down or leaked fluid from the cueing system in your TT. It is $10.
Take off the lifting rack by loosening the set screw.
In the Rega, there is a 2 pin tool to remove the top of the cylinder housing. You may be able to use 2 small nails driven thru a small piece of wood(at the proper spacing) as a spanner to remove this. Take out the piston. Clean out the cylinder with alcohol and a Q-tip. Replacement is a guessing game, because you don't know how much to put in. Try an amount, re-assemble, and see if it is enough. If it goes up all the way it is enough. If it is too stiff to move, it is too much. If it goes up too little it is not enough.
If you don't feel comfortable with doing this, take it to your nearest Rega dealer.