Dan- I converted my PW 2026 a while back. The pellet smoker still worked but I wanted to update to a fluid unit. Real easy project. The little hole in the bottom allows the "puff' to happen when the driver cam rotates around and lifts the piston.
What I did with my 2026 was tear it down and clean out all that waxy mess of a buildup from the SP pellets all those years and freed up the piston. Then I replaced the wick and added a spring which it did not have.
Thereafter I have been using JT's liquid smoke fluid and it is working better than ever. Lasts a long time too. It puffs much better because of the spring.