Lady Diana

Many Janomes had this problem. Janome has a latch on the take up levers now. They know about this problem. So far they have not designed a fix for existing machines
I thread my take up lever from the left side...no problem.
BTW you have to physically lift up your pressure foot before threading, not just look. This will open the tension disc to allow your thread to rest fully inside the tension discs.
I Love my 6600's. One at home, one at the cabin.
best wishes for a good fix for your issue.

EasyPeezy

Let me try to explain. Check this video on youtube
https://www.youtube.com/watch?v=tZOsK2STIbw
and at around 7.14 he starts explaining how to thread the machine. Right at
7.24 after the thread goes through the tensioner...usually you would go the
right of the take up lever. Instead of going right...you go left. In other words
the thread will cross itself at the take up lever.
I took a picture of my machine to show where you are supposed to go
left to right. Hope this helps.

Karamarie

I also have found threading the uptake lever from the left to right seems to work for me also.

lindaschipper

I have the 6500P and it does this also...thread from left to right on the take up lever as someone else suggested.