Seeking drum sander help

[SoftWood]

I have a dual drum sander that is giving me grief, would love an opinion on a solution.  
It's a Powermatic sander that I bought new several years ago.  It worked perfectly until I mistakenly played with the pressure rollers.  Now I don't know where I am from baseline or which one is out of setting.  I tried contacting their customer service to help me with a factory setting but they weren't able to give me one.  
I'm feeding 18-20" pieces through it and it is sanding too deep on the front 4" of each piece, it's a uniform amount, looks identical on each piece and it is from the 2nd drum, almost as if the piece is raising up off the bed into the drum.  In my thinking it is because the pressure rollers aren't holding the piece down but Powermatic said the opposite and thought the rollers weren't giving too much pressure on the rear of the piece causing the front to rise.  I tried going each way with the rollers, tighter and looser but cannot get it to stop. 

Has anyone setup their hold down rollers using a measurement?  

[teakwood]

Can not help you with the pressure on the rollers but i had a hard time adjusting the two sand drums. it's just a terrible system in my opinion. the second drum is for nothing if you need to make several passes. and the machines lack power for two drum sanding. so my solution was to just raise the second roller and use it as a single drum sander. the finish sanding i did with a orbital hand sander. a drum sander also leaves straight sanding lines in the piece. just not comparable to a real wide band sander.

[rusticretreater]

I have viewed a Powermatic dual drum manual and am amazed at how little information they provide on making these adjustments.

Since I don't know the exact model of your drum sander, I viewed the one that came up in a search online.

Page 11 of this manual covers pressure roller adjustment and states that snipe, the condition you have, is caused by too much pressure on the outfeed roller.

https://powermatic.com/media/akeneo_connector/asset_files/1/7/1792244_man_en_d18f.pdf

I would raise the second drum up high so that it is not making contact and run some stock through, having the first drum sand the surface and watch what happens at the second drum/roller area.

[jcbrotz]

Are you sure your in-feed table is level? I've only dealt with 2 dual drums the one did similar and the in-feed was running uphill and the 2n pressure roller leveled out the board so it went flat