Some time ago the bird bi-directional charger stopped working and now the aux start relay stopped working.Had to fix one of them. I disconnected the negative battery lead on both banks to ground making certain all voltage is off the solenoid. Removed the cover and the bezel to gain access. After that it was just a matter of swapping out the old one with the new one. Found the OME replacement Trombetta 12 Volt Bear DC Contactor Part No. 114-1211-020 on amazon.com $59.37 I have not made up my mind on replacing the Bird system yet.