One of the first things I did with my PT145 (after thoroughly cleaning the firing pin channel) was to do a little light deburring with 600 grit sandpaper on the firing pin itself. Then I rolled it up tightly and and ran it in and out of the channel itself. You need to take the firing pin block out for this, which means you have to detail strip the upper (with the exception of the key lock). There are a number of openings inside the channel, and any one of them is a candidate for a raised edge that could drag on the firing pin which is why I did the polishing inside the channel.
While you've got it out, take a good look at the firing pin block. I found some peening on mine which I removed with a needle file, followed by a little polishing. It was dragging on my firing pin enough to cause the odd light strike. Take a close look at the firing pin when you first remove it, and see if you noticed any unusually shiny areas - might point you to the area that's causing the problem.
When I reassemble mine I always use Rem Dri Lube with Teflon. It's cleaner than graphite, and teflon is just about the slipperiest substance known to man. I give it a short spray in the firing pin channel, on the firing pin itself, the inside of the firing pin, and the firing pin spring. I clean the firing pin and channel every time I clean the pistol with a Q-Tip and solvent, and I pay particular attention to the end of the firing pin channel. I also run pipe cleaners through the hole the firing pin passes through on it's way to the primers just to make sure nothing is catching there. I do this religiously and I can't remember the last time I had a light strike. Best I can do for you.