Machine settings and actual volt/amp output are two different animals. Best approach to this would be to get some help and an appropriate Volt/Amp meter. Record your values from the machine(s) at work that are performing properly for you and then try to duplicate those same values with your sa200. Duplicate all variables...pipe size, material, electrode size and maufacture, EXACT position & height, same arm rest, same stinger..... It is very easy to change something and not realize it when practicing at home. Might even want to invite your shop Foreman over and have him breathe down your neck too (LOL).
OMG!!! A Trailblazer out performing an SA 200 is sacrelidge in these pages. Better get this sorted out soon!!!!
good luck

Have you tried stoning the armatures? I don't know if that will help but it is worth a try. Check your brushes.
Floyd

How is you body positioning? Make sure you are as comfortable as possible. Are there some variables at home versus work that are different in regard to how you are setting yourself up? I know that if I am not under the pipe far enough and uncomfortable, then it is much harder to keep the bottom looking tight without undercut, especially with the 3's. Plus realize that the two machines do definitely have different arc characteristics and IMO require some subtle changes to the way it happens on the bottom in particular from one machine to the other. Try cooling off just a bit more as you are reaching 5:30 and sometimes even through 6:30 if need be. Depending on just how much heat you have built up contributes enormously to how well the bottom is going to successfully fill. Remember 3 of the things that affect undercut: 1-Heat, 2- Travel speed, 3- Rod angle. Also a fourth would be your Arc gap. I like to keep it as tight as I can and still maintain a decent puddle without snuffing it out. Others may do this a bit differently, but this seems to be working for me.