If you just got your ZF rebuilt, it seems to me that the rebuilder should be willing to offer advice on getting it to shift. Also, if you used a Pantera specific clutch, the vendor should be willing to help too.
I paid well north of $4000 to get my ZF done and believe me, I wasn't shy about asking questions when it came time to put it in.
I'd start ringing their phones off the hook. Don't feel like you have to figure it out all by yourself.
Mooso.
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