The hybrid IC's are available online, but the problem is changing them, I haven't heard of a good method of removing them as yet. Some say to buy a pair and change the Zsus IC at the same time. Save a lot of hassle and get the 3 board kit.
P.S. Check if you have a short between Ysus fuse and earth, tells you if IC is gone. Buffers can also blow Ysus IC, check Buffer IC's for damage, and worse of all the panel could be faulty. Guesswork seems to be the name of the game with plasmas at the moment.