Hi, my plumbot have 10 skills 'bot building', but unlock more chip slots is not possible. I tried it on on her own and on another plumbot, still the same message 'you need 7 (and more..) skills to unlock this slot. What am I doing wrong? Thanks a lot

As far as I know, 7 slots is the limit, unless you make a mod that changes that. I looked into it, but it's above my pay grade to make. Bots with limitless learning can learn normal Sim skills, like playing chess or bot building, etc. If the bot builder has low skill, the bot may have fewer than chip slots, and a low quality. This can be changed by either the Sim, or the bot, increasing bot skill. When skill is high enough, the option to "upgrade chip slots" will appear when clicking on the bot... by either a Sim, or the bot, if it learns bot building skill. Quality will increase during tune ups... according to skill.

Nraas Master Controller has a cheat for chip slots, trait chips, and (I think) bot quality.