Ah, I did that once. Cleaned the rollers, forgot the disc. It’s okay! We’re human. Your press forgives you.
I clean the rollers and disc on my Pilot with Crisco, believe it or not. Get a big hunk of it (1/4 cup?) and rub it into the ink with a cloth until it loosens up. It’s going to take a while, but it should work. Once the ink is loosened, Mineral Spirits work really for the final step to get all the ink off.
When this happened to me, there were a few small patches that I could not budge from the disc. I used (with great hesitation) steel wool to get them off. Shockingly, it did not scratch the disc at all and got the ink right off. I used a light hand though, and would NOT recommend using it for large areas.
Good luck!
Samantha