My Shop Fox Mortiser Always Burns Lumber! Help!

I have a shopfox benchtop mortiser that ALWAYS burns the stock I am trying to mortise. I tried readjusting the chisels, I tried going at incredibly slow feed rates, and there is always a lot of smoke coming form the stock and a lot of burning. I thought maybe it was the chisel part of the bit, so I took it out to use just the drill bit and it still causes just as much burning. Chisels are BRAND NEW and Shop Fox brand. I tried mortising on walnut and cedar and both had the same results. If you guys have any ideas or tips that would be great!

Thank you!