The fork seal is probably leaking. Either the seal is worn or it's dirty/gritty. There may a youtube video.
The 1000P was pretty much unchanged through the entire model run from 82-2005, and the forks are similar to most KZ forks.
You'll need the manuals for your model. The base manual is the 81-83 KZ1000/KZ1100 chain drive manual, then you'd also need the supplement manual that covers the 2000 KZ1000-P19. There is a base manual pdf available on the internet at various places. KZRider. maybe KZ1000R.com.
The fork caps & bottom allen bolts can be stuck. I applied heat using a propane torch.
An air impact wrench is handy for removing the bottom allen bolts as they can be a bear to remove. heat helps.
OEM fork seals are preferable. some dealers sell aftermarket, so beware.
I installed K&L fork seals on my 81 KZ650. made in Japan.