Like both Fixit and Toolbox, Cinch is one of the many Mini-Con prison guards on board the Alchemor. Like the rest of Fixit's cousins, Cinch was enslaved by Glowstrike, Saberhorn, and Scorponok after the Alchemor crashed.
Transformers Robots in Disguise
History
Following the crash of the Alchemor, the freed prisoners revolted against their Mini-Con captors. Cinch and his comrades were fitted with inhibitor collars, and put to work rebuilding the wrecked stern of the prison ship.
Season 2
In Decepticon Island (Part 1), Cinch spotted and was excited to see Toolbox's return, which alerted two Vehicons to the Bee Team's sneaking in the Decepticon island.
In Decepticon Island (Part 2), Cinch was most likely one of many Mini-Cons freed from his collar and called on by Toolbox to help Optimus Prime and Bumblebee fight a powered up Steeljaw. With the Mini-Cons using their system probes to make Steeljaw drop his weapon, it worked and all of the Mini-Cons along with the Autobots escape before the stasis bomb could go off. With the Decepticons all back in stasis, Cinch and his fellow Mini-Cons elected to complete the Alchemor's repairs and return to Cybertron, taking with them the Decepticon prisoners, Optimus, Windblade, Ratchet, and Undertone, who had also joined the group for this mission.