My West push feeder stopped pushing suddenly. I checked the needle length and found that the same as N and E, but the arm itself did not go far enough down, so the needle did not go down far enough, and just scratched the tapes.
Adjusting the needle length dir more harm, long enough to push the tapes the needles ripped up all cover tapes on the feeder bank, so that was not the way to do it.

I was in the middle of a large jop and started to disassemble the feeder head.
I found a small screw to be there to adjust the way the arm can move down. It turned out to be very very tight, it was glued into the arm.
After heating the arm I was able to loosen the screw, in fact it was 2 screws, one countering the other. I could adjust the arm, so it moved 6.5mm down, just as the other feeders did. Before it was only 5.5mm.

On reassembling the screw I found that it was very easy to undo the adjustment by countering the first screw with the second, just a slight bit of more torque changed the way of movement a millimeter.
So you need to take care of this and remeasure. I guess in the factory this was not done very carefully, and now I also know why I often had misfeeds on the W-feeder. As long as the needles were new it was barely enough to feed.
Now the feeder works much better. I also adjusted the small screws on the side, as my slider was very tight.

However, if someone finds a feeder stops feeding suddenly, you will probably need to adjust this screw, which is only possible when disassembled, the screws are way to tight to turn them when assembled.
You need to heat up the arm to destroy the glue.

Be carefull when you adjust the needles, as I did first, if you make them too long it will rip out all cover tapes when moving!
Better is to adjust the movement as I did with the small screw.