are you sure the HF is drawing properly?
they stop drawing completely at 200 degrees
as others have mentioned, sometimes you can only do as good as can possibly be done
you need a good pre-spray that's safe for stain resist and a "sledgehammer"
Sledgehammer's that I have personal experience with are;
Number One on my list is
Prochem Powerburst
It's been our "go to" sledgehammer for quite a few years.
I've done side by side comparisons with many juices in ratholes
Nothing I've tried has been better than PB.
the over whelming majority were clearly inferior to PB and only a couple have equaled it
It's an excellent pre-spray that covers a broad range of different soils
Bridgepoint PowerBreak
One of the very few that will equal Powerburst's efficacy
I hate the smell of it though as it dwells
DSC Relief ...similar to P-Break...I don't like the smell during dwell time
but it kicks azz too
Chemspec Enzall ..it rocks
I don't care for the way it mixes though and had some issues with clogged filter/screens in our electric sprayers
Bridgepoint Flex
a wicked potion of heavy butyl and lye
melts grease like butta..
unfortunately, the top four are all powders and a PITA to mix strong in a Hydroforce
your best bet is to do side by side evaluations in the empty ratholes.
Yea I know it takes more time...yea I know it's a bit of a PITA changing juices.
But it's the ONLY way I know of to separate the wheat from the chaff.
otherwise you're just taking someone's word for it and you'll never really "know"
..L.T.A.