How frustrating. Here is a manual with really the best tension rebuilding info I have ever seen. You need two people, then go through it together sentence by sentence, word by word and you will be able to fix that tension. Here is the link: http://www.tfsr.org/publications/tec...achine_manual/
Miriam is correct. I've been working on a couple machines with the same tension systems and that manual is a real help. Read it, look at the pics and then look at your machine's tension and do it.
I did it with out a second person, but an assistant helps.