I am doing a valve job on a Kohler CV15T Spec 41579. I decided at the last minute to change out lifters but they only had one. When I pulled my lifters and tried to push down on them they were rock solid. The new lifter could easily be pushed down with the connection rod. So I assumed the new one needed oil so I put it in a can of oil and push it up/down 50 times took it out and it went up/down fine. I took the old one apart and sure enough there was oil in the bottom under the plunger. I poured it out and put it together and lifter worked fine. I put it in a glass of oil and 1 hr later it was rock solid again. Can I assume that the hydraulic lifters are bad. There is no adjustment on this Kohler...single cylinder. Kinda hard to believe 2 of them are bad.