IR filter for old home tube camera question

[ARC Tech-109]

That blue filter is also used by Sony professional cameras and is known to cloud over time. You can remove and replace it with a standard piece of glass as this also affects the focal path thus the reason for the focus issue. I don't know how effective an external IR filter would be or how sensitive the old vidicon tube is to infrared. The red tint is the result of the camera calibration to counter the blue filter and you will need to counter this.