I have had good luck with my P90 highcap. Here is a link to some info on ensuring your P90 high caps are more reliable. good reading.
about 12 posts down "binatang" posts a picture of a mod. I did this to mine and it works great.
http://www.airsoftplayers.com/forum/...?TOPIC_ID=5365
Note: I used different material though... I cut a small strip out of aluminum from a pop can, bent it into a little V shape, a drop of super glue in place taking care not to get any on the gears, and filled it in with hot glue. Don't make it to big.