CAT SG18B Stump Grinder need help

[Ridgeriders1]

I have a Cat 272D2 XHP and purchased a new Cat SG18B Stump Grinder, make a long story short, delivered with standard flow couplers, everything worked fine, except it over heated my hydro oil. Talked to tech, he said it needs High Flow couplers, we switched them out, its 3 hydro lines and a electric harness. When I activated the thumb wheel and the switches next to the wheel it was fine. When activating the left stick (# 5 &6) press and hold then activate right stick (#3 or 4) to raise or push in and out the grinder stopped running but you could still swing left or right. When activating 5 or 6 + 3 or 4 it would temporarily run the grinder. High Flow indicator light did come on! At low idle grinder would run fine, at half throttle it would stop or run temporarily. Tech thought that maybe I had the couplers switched, so I swapped them out. Long hose off of top of hydro motor was a male, switched to female coupler, same with short hose. Ran machine everything worked great! But high flow light does not come on! It is advertised as a high flow attachment, it is hooked up to high flow, the saw does turn counterclockwise when looking at motor side. Question: Which hose should have the corresponding coupler? And how important is the high flow indicator? In other words I do not want to damage the unit by running it backwards when increasing rpm’s, no damage the machines hydro pump by same! If I had it correct the first time, then why does it shut down the grinder but yet still move the attachment around? Every time you move it it turns on briefly and shuts down briefly when moving it. Thank you for your help!