Well you know how to adjust the trigger? Undo the lockscrew on the side and then wind the trigger adjust screw in. You can wind it in to the point where the sear wont engage and then start to back it off. It is up to you to decide what is "safe". I am not a fan of the Premier triggers as when they start to get good, is the point when the sear is about to give up the ghost. I think early ones had a sintered sear which once it starts to wear , wears very quickly. At some point they went to steel sears.
What i would do is remove the piston and check for any nicks on the holding face. I have heard that many years ago some match shooters would put a 5 degree radius on the face but with the spares getting harder to find, I wouldnt do it now.
Then have a look at the trigger. Often a really bad trigger is the result of a crushed trigger spring. Stone the sides of the trigger and sear to make sure they are not catching in the sides of the housing and give the housing a clean. Relube them and the pins and try the gun, then adjust the trigger. If it is still bad than I would be tempted to take 2-3 coils off the mainspring. You dont lose a lot of power but it does make the thing easier to use and a lighter trigger.