The same thing happened to me and I found that I needed to change the way I used it, instead of pressing it against myself firmly the way I used to, I just leave a little bit of space between my body and the stp. I'm not sure why but it seems like it straightens out the stream. I don't know if that helps or not.
I don't usually use my stp all the time, but there are times when it is really handy to have it with you, (camping, road trips, sporting events) and it's really worth the effort to be good at it if you enjoy activities like that. I'm sure you'll figure it out!
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