had purchased the ct518d it was doa. you guys replaced it quick and without any problems.recieved the new one wired it up worked very good,was very inpressed with the way it welded. now it has quit working hasent burned 10# of 3/32 rod with it ,called and alec said to send it back and they will take care of it ,thank you very much. the question i have is there an upgraded unit that would be more reliable and how much would it cost me to upgrade to a more reliable machine? thanks for all the help.