Login and browsing the PCASDR Classifieds works for me using Firefox and Safari, but creating new ads doesn't work. IMO there is no doubt this old Classifieds site needs upgrading or replacing. A possible cause could also be that browsers have evolved while the Classifieds site hasn't.
I never understood why we were not allowed to post Ads on the forum anyway, most forums have a Classifieds section. With the Witness now only being published quarterly, maybe it's time.