You need to contact Pella. My clients just got new Windows when that happened. The first ones like that couldn't be fixed. Never used them again. Hopefully yours are newer.
If your Pella blinds are between the glass panes and operated via a slide lever rather than the small twist dial, you've probably discovered that this was a frequent problem for other homeowners, as posted on blog sites.
Try contacting Pella Corporation headquarters for assistance, as suggested.
If your interior pane of glass permits access to the blinds, you may have other replacement options.
My Pella in-between blinds are 25 years old. I just ordered 0.9 blind cord from the internet and using an upholstery needle I rethreaded the blind. You must take off the guard by first removing the end caps. Using the needle thread the cord through the top of the window pane after pushing the blind to the top so it is easier to thread through all the entry holes. Do not cut the string until you have through all the eyes of the blind and then extended the blind down to the bottom of the pane of glass. Leave a handy amount of extra string before knotting the string on the end cap.
I have a plastic chair mat under my computer desk that the edges are curled and won't lay flat. Have been unable to bend them back as the plastic is hard
This post may help you with your blinds https://homeguides.sfgate.com/restring-broken-blinds-strings-52976.html
If your Pella blinds are between the glass panes and operated via a slide lever rather than the small twist dial, you've probably discovered that this was a frequent problem for other homeowners, as posted on blog sites.
Try contacting Pella Corporation headquarters for assistance, as suggested.
If your interior pane of glass permits access to the blinds, you may have other replacement options.
My Pella in-between blinds are 25 years old. I just ordered 0.9 blind cord from the internet and using an upholstery needle I rethreaded the blind. You must take off the guard by first removing the end caps. Using the needle thread the cord through the top of the window pane after pushing the blind to the top so it is easier to thread through all the entry holes. Do not cut the string until you have through all the eyes of the blind and then extended the blind down to the bottom of the pane of glass. Leave a handy amount of extra string before knotting the string on the end cap.