Our customer still using it. Now this product is needed for repair. Can you send me EOL-notification or any letter about it? We need official confirmation.
You'd have to find them on the secondary market, or find an equivalent/substitute part, might need to look at faster part, or one with or without the quartz window.
OTP in this context being an EPROM encapsulated in plastic, where you can't expose the die to UV light.
Customer would need to hold stock of parts, and have .HEX or .BIN describing content, and a programmer capable of programming.