JAM, I am glad you are back. Folks thought you fell off the earth. Several will get in touch and give you some real help.
I have read all the posts and this post has some good info.
If your temps are jumping all over the place, it is probably in 1) the controller, maybe it is wet? 2) Thermocouples, broken wire or wire loose at the controller. 3) connections for the heating element. 4) power cord.
Hang in there. You have willing and able assortment of comrades here.