Yes, I was breaking direct drive belts. This was happening in wet high yielding corn. Check your sprockets, I believe they had 16 teeth on the driven and 13 on the driver but I could be mistaken. The only other option is to change over the constant speed, and be happy with 3.5 to 4.0 mph. I talked to a few dealers and they told me not to push these heads, because the combine can't handle it. Every dealer I talked to said these heads are great but don't push the combine!! There is a few other checks to do and that is the clearances from rotor to concave on the head which I already assumed you had done. I beleive it is supposed to be 2.5mm at the top and 1.5mm near the bottom. If these clearances are not met the corn head will call for more power.