Stay FBM or switch to FBA for used office electronics

We mostly sell used calculators and have been doing FBM since we started a few months ago. It’s a mix between FBM sellers and FBA sellers. Usually never get the buy box since there is over 100 sellers on one ASIN. We have sent in new units only to FBA and those have sold pretty fast (or some that have been pending for a few weeks). Wondering if it would be better to send in some to FBA. Also would be a little hard to track serials that way. Thoughts?