I mentioned having contacted Korky about whether the cap was the same. They were nice to reply:
Good morning,
Thank you for your email. Yes, it may need to be serviced. Is your unit a blue
G-Max? if so, then you can service the unit and purchase the cap assembly from
Home Depot.
https://www.homedepot.com/p/Korky-Toilet-Fill-Valve-Replacement-Cap-R528CM/20266
6007
below is a link on how to service the unit, if indeed, it is a G-Max fill valve
or Korky.
( fun video )
Please let me know if you have any questions.
Thank you very much,
Tara Petrozelli
Customer Service Rep.
Lavelle Industries, Inc.
PH: (800)528-3553
Fax: (262)763-5607
So with that in mind, their link says that Home Depot DOES sell the R528. So I checked local stock and found 3 at the store near me, where they told me they didn't have them yesterday. I just went back, armed with a printed page from the site, and found them myself.
So I brought it home and changed it just now. Before this, I guess I didn't have a comparison between the old and new ones. The PROBLEM was that the rubber gasket on the old one was actually STUCK to the top if the piece below the cap! Ack! SO I just peeled it out and changed to the new one, put it back together, turned the water on, and...the toilet didn't refill at all! What the...???!
SO I opened it up again, took the new cap out, and pulled the rubber gasket up a little, with my fingernail, just to see, then put it back, and it started refilling again, but VERY slow - maybe taking 4-5 times as long as the tank refills before. Anyone have any idea why? I'm stuck with a very slow filling toilet now, and I don't like sitting around waiting, if you get my drift.