I have been using a PMI twist ascender as a chest ascender in my frog setup for the past 13 months or so. In that time I have climbed somewhere in the neighborhood of 13,000 feet, mostly on dirty/muddy ropes. As of the last two days the ascender has started to slip a high percentage of time. Yesterday we rappelled a 150 foot cliff, and on the way back up I started to notice some slippage. Today in the backyard running through a 360 foot rope the slippage continued to worsen. The first 300 feet or so it was probably slipping every 20 strokes or so, however by the end of the second time through the rope it was slipping every stroke. As this is my first PMI heightec ascender I don't really know what to expect for a lifespan. Looking at the teeth, they appear to be quite worn, especially the upper most left tooth. Comparing it to a new twist ascender the teeth feel significantly duller. This seems to indicate that the ascender is wearing out, however it seems like if this is indeed the case, the lifespan on this ascender is particularly short. I'm curious if this short lifespan falls inline with what other hieghtec ascender/croll users are experiencing? Any input would be appreciated. I have also attached a couple of pictures of the ascender so you guys can see the wear I'm talking about. If you think it shouldn't be affecting its grab ability, please let me know. I felt like I was using pretty good form but I don't know.