That sound like a lot of work. I don't see any problem with it being set too high. Now if it was set too low then you might see a performance problem. If the sprinklers seem to be operating properly I'd just wait and see if any problems arise. I'm betting none do. Here's a couple of links for you.
http://www.rainbird.com/pdf/diy/man_R50.pdf
http://www.rainbird.com/diy/products/rotors/chart_tdr2_r50.htm
If I can't fix it, it's broken!