The "vacuum won't shut off" problem is caused by a faulty triac (electronic component) on the P.C.B. assembly. You have two choices, depending on your handiness:
1. Easiest: Replace the PCB: P.N.=KC86WBZRZ000
2. More difficult: Replace the triac: BTA16-600CW (ST Microelectronics): http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00002265.pdf
The PCB costs about $25.00 (incl. shipping) from Sears, whereas the triac costs about $1.50. Sears will not sell the triac - you'll have to find an electronics parts supplier.
You may be able to find a cheap P.C.B. (printed circuit board) on EBay.
feather5000
April 2011