1702A EPROM Programming

I've been working with someone who has an old 8080-based single board computer he's trying to get to work. We're investigating several possible problems but it's starting to look like there's a problem with the EPROM. I have the ROM code he needs and will be checking out the EPROMS, but we may be faced with a need to reprogram one or both of these. They're the old 256 byte 1702A Intel chips (ceramic). I've only programmed the 27xx series but have read that the 1702's are "really difficult" to program. Was wondering if folks in this group could comment on how to proceed if/when we decide we need to reprogram one of these. Are there more modern plug compatible alternatives? We may also need to replace one or both - any sources known other than eBay? thanks. p.s. FYI, the computer here is the "MMD-1", an old 8080 trainer/breadboarding box. here's a picture i found on the web: http://online.sfsu.edu/~hl/c.E&L-MMD1.html - glenn