When you say completely broke ya mean the strings?? if so you can restring them which I have done MANY times and the Big back one as well,you can buy the roll of string(better Quality) to do the job and also there are many videos on You Tube on how to do it ,the first time you do it will take a while but you will get the hang of it and be a Pro like ME after about 20 times of doing it
here is a link for the repair kits
http://www.fixmyblinds.com/RV-Day-Ni...arts-s/134.htm