Upon investigation in lab into optode and ctd pump: optode cable culprit. Unflexed it wasn't working, flexed it worked intermittently. A bit better not being torqued by the rope backwards. Problem seemed to be closer to the bulky end where it plugs into glider. CTD pump: No obstructions visually. The pump seemed to be spinning but sounded weak and looked like it was spinning very slowly. No water introduced into the pump yet. Emailing SB before doing anything further.