In the process of trying to resurrect a neglected '87 Isuzu Trooper, I rebuilt the carburetor. However, I have had trouble adjusting it (RPM's don't stabilize, seems to still run rich even with mixture screw in all the way).

In the process of rebuilding I MAY have damaged the power valve, but I couldn't remove it to check, and wanted to get some feedback about it.

When I tried to remove the power valve, I just used a regular screwdriver WITHOUT notching the center (I later learned that a notched screwdriver apparently is required to keep from pressing down on the tiny rod in the center). I tried as hard as reasonably possible to remove the power valve, but I only succeeded in stripping the head (brass) and also applying a lot of pressure onto the tiny rod.

Would this pressure of the screwdriver on the rod of the power valve damage it sufficiently to allow an excessive amount of fuel to go through it?

If I have to replace the power valve, I assume that the only way to remove it is to drill it out, unless there is some other recommendation.

Thanks.

Martin