All the usual suspects in 400-day clocks are there with a vengeance in the miniature movements, and I think you're stuck with the mainspring you have. Did you polish the pivots? This is particularly important when dealing with a movement such as this one that has minimal excess power. Is the beat set correctly? With minimum supplemental arc, the beat has to be spot on to get maximum running time from it. There's really nothing magical about the pin pallet escapement; it's just a bit different than the Graham. I agree with Kurt - go back to the basics and make it absolutely perfect. I have one like yours that runs well - I wind it during daylight savings time changes, so I know it will run at least six months on a winding.
After polishing the pivots, I find that installing one wheel at a time and checking for friction, straightness and end float is a worthwhile exercise, followed by two at a time looking for any binding or interference, and so on, until the whole movement is built up minus the anchor. Then the two-click test is a good indicator of how well the movement is set up. If it goes into motion with no more than two or three clicks, then you are assured the works is set up well and has minimum friction. If, after installing the anchor, the clock still stalls, that's indicative of a problem in the escapement, such as beat, position of the fork, clearance between the fork and anchor pin, or a damaged suspension spring.
One final thing - from my experience, all Komas are really sensitive to the tightness of the hand nut. Too tight and they stall. Too loose and the minute hand just drops uselessly to the "6" position. And the range between the two extremes is small. You might start by just loosening the hand nut and see if the clock runs, even if the hands are not advancing.
Good luck - this is a cute little clock that is enjoyable to watch running alongside its bigger cousins.