My two experiences with this failure mode have been lack of a deep pan that resulted in lack of fluid in high gear only, and just last year or so, lack of valve body pressure....The later I had it turned up to the proper amount. It was CRT that found this issue. We weren't sure why as it was the second time my 605 lightly burnt the clutches. I already have the 5 gear setup, just not the complication of an aluminum billet drum, mine is steel...I do not know what the proper pressure is or how he checks it, but runs good now....