follow the drip evidence, like a detective would.
as you pass a hose, remember the trail, up over the thingy,
down into the dark abyss... when you find where it stops, thats where its leaking.
Give the machine a complete makeover. pull the forks, replace the oils, check everything,(block and blueprint that engine)
bore and stroke it, add some real accessories, and tweak the paintjob. a new seat would be not as wet on the rear, and when a machine starts failing, it usually continues failing until the rider gets hurt someway and just forgets it.
Understand. these toys are called million dollar babies because of what it costs to keep them in running order.(i think...)