I've just been wrangling with a 25ish year old Kenwood stereo. There were some connectors on it that I couldn't work out - which led me to this guide. The specific connectors aren't shown here. It turns out theybare spring-loaded, and you have to push the upper part (that I initially thought was a plug) down into the board - and this releases the ribbon cable. On the stereo, there are some shorter ones (8-pin), and some longer ones (15pin). On the longer ones, if you look close enough, they helpfully say ‘push' on them.
I've taken some photos of you'd like to add them to this guide?