Welding Tips and Tricks

I have recently started with a company that overlays Stellite 6 on to the o.d. of 316 s.s. round bar that gets machined down and turned in to valve plugs. They have been doing this for a couple years and have never much success with producing welds with out subsurface defects, which are found after the part is machined. We have no problem producing good welds by hand with tig, it seems to only be with the automatic tig and I would assume it has a lot to do with the fact it uses a "flux core" wire. I have contacted a few different wire suppliers and have not had a lot of success dealing with them. I was hoping someone on here has overlaid with Stellite 6 on an automatic machine. We have a AMET XM fixture/controller with a Maxstar 350 power source, 0.45 welding Alloys 6-tig wire. I have researched this ton and cant find any info on Automatic cladding but have found lots on by hand tig welding. What I was hoping to get specific starting parameters from someone, that i might just have to fine tune.
So, Kind of tungsten? size of nozzle? Gas Lens? amps? volts? wire speed? Velocity of part? width of oscillation? slew time? torch position? pulse or not?

Any info would be so greatly appreciated

Thanks