I am trying to find where I add Hydraulic Fluid on my BX1500. I have found the dipstick to check it but can not seem to locate the cap to add more fluid. I have seen videos which all show other BX models, but the 1500 does not seem to be in the same location. I have also looked in my user manual and this shows how to drain it, check it, change filter, but it does not show where to add it.