[aivonline]

I've recently bought Walther PPS First Edition, manufacture year code is AH.
I've encountered the same issue of gritty take-up and especially gritty reset, which I hate as am spoiled by my Walther PPQ trigger.
I tend to agree that the grittiness to a larger extent should be attributed to the striker spring's friction against the striker well walls and the striker axis.
I've disassembled the striker assembly and it turns out the striker axis surface is noticeably rough. I can feel it distinctly when sweeping nail along the striker axis.
Besides, it has a noticeable hump halfway through the thicker part.
For curiosity's sake I disassembled a PPQ striker. It is polished and has a form that minimizes spring contact with the striker axis.
See a pic for comparison, PPS striker (top) vs. PPQ striker (bottom).

 

[aivonline]

I have polished the striker as suggested in the topic. It did help a bit.

I further disassembled the trigger mechanism and polished the trigger bar guide (part 12.8) on the inside, where trigger bar travels along. The trigger became smoother but still there was enough room for improvement.

Taking a step further, I compared striker springs of my Walther PPQ and PPS. They a almost identical, only the PPQ's spring is a tad shorter. I thought that a shorter spring would result in less spring bulging when compressed thus making less friction in the striker well.
Guess what I did next - yeah, I swapped striker springs between PPQ and PPS.
After all mods my PPS trigger with a shorter PPQ striker spring became really smooth.
On PPQ I didn't notice any change in trigger pull or smoothness with the PPS spring - just as before, a superb smooth light excellent PPQ trigger.
Test firing has shown that PPS with PPQ striker spring functions just as reliable as with the original spring.
Check the pic below - PPS (black, longer, top) and PPQ (white, shorter, bottom) striker springs side by side:
http://i637.photobucket.com/albums/uu91/aivonline/Walther PPS/IMG_3196-1.jpg