Dear Mary LInford,
Stuller owned Swest prior to closing Swest in 2003. They have the
responsibility for supporting Swest customers (Stuller
1-800-877-7777). Your Swest furnace controller model DTC-617 was
made by Paragon Industries (Paragon 1-800-876-4328). If you talk with
Paragon you must tell them your unit is a "12 button controller with
the Swest programs in it". You will need to accurately describe it
to them because there were several versions of this controller. You
are always welcome to call or email us (The Jewelry Equipment Dr.
The problem of not holding the 900 degree temp when it gets to the
last step sounds like a possible thermocouple problem. If you try a
good thermocouple to verify the problem, you must use a "Type K"
thermocouple with this furnace controller. I hope this helps.