ITV For Schools - Maths is Fun (TX: 17/05/1991) - Betamax (Unintended switch to B&W???)

Now this one is very frustrating. The Tape flicks to Black and White around half way through "Maths is Fun" and on several other episodes I have very luckily found on this tape of "ITV For Schools". I have wound the tape back and it is colour still; I have checked VHS through my rig, they are colour, I have checked other Betamaxes and they are colour, and I have loaded up menus on my Time Base Converter; all colour present. So it must have happened during recording 35 years ago! It's a shame, but what can I do?! Please try to enjoy still. Running Order is as follows: ITV For Schools Slate "Maths is Fun" Follows Shortly Slate Maths is Fun Slate/Sting Match Spinner Promo "iTV For Schools: Maths is Fun" Please feel free to add anything. No Infringements Intended. TX: 1990