Where to find replacement screens for TI-30XB Multiveiw?

First, I would recommend checking the ribbon flex to the LCD. It could be the problem, and the LCD is actually fine.

If you do need to replace the LCD, there is a replacement guide here. Be aware that soldering is required. Also, I would recommend desoldering the ribbon flex, not just ripping it off as is suggested in the replacement guide.

I believe the TI-30XB uses a 16x4 line dot-matrix display, but I can’t find it anywhere. Calculators are notoriously hard to find parts for - replacement parts for the TI-30XB may not be available at all. You may need to find a ‘donor’ calculator to supply the screen. I would start by looking for some old TI-30XB’s or XS’s on eBay and using them for parts.

You could contact the guys at CalculatorSource - if anyone can help to source parts; they can. Their contact details are here.