I was using my mm200 tonight and it was intermittently feeding erratically and making a very noticeable, loud, not normal hum only when I pulled the trigger. When it was doing this it had nearly no output, it would just sort of fizzle . I checked everything and it just started working, I welded for about 1 hour on and off and the fan cycled and it worked as normal. I did another set up and it would not weld, lately it seems to need to be on a higher setting to weld, it smelled hot and when I opened it the transformer was hot to the touch but the fan had been cycling any help would be appreciated I love this welder and am kind of bummed that is not working.