It only happens about once a fortnight, it's not a great problem, it's only a minor inconvenience, it re-engages straight away, we only fly VMC, it's intermittant, it takes time and money to experiment replacing bits, it's the only aircraft we've got, they think it's the gyro, it will be replaced when convenient, we don't go inadvertant.
PS. The transfer pumps work fine. Thanks for your answer on that. It's always nice to find the answer to something your not sure of.