Hello , can anyone help me if you have faced a similar issue as what I am In - my 37 more Sany concrete pump based on a Isuzu chassis, after engaging the PTO , the RPM is not raising up due to the speed not working , what could be the most anticipated cause of if either any sensors or maybe electrical fault n if so where at , please would appreciate any assistance on this ,also does anyone have service manual for 37meter Sany concrete pump