Have just purchased SN 129 and we have an electrical problem. After testing/replacing all the piping of the engine: With the alternator off, the oil pressure switch operates normally. Switch the alternator on and the oil pressure drops to nil which is most disconcerting. We have cleaned out the the oil line to the sender and primed it to be sure. Also, I have a new battery but with the alternator on, switching on all the electrics (radio, fuel pump, AH, DG, beacon, nav lights etc.), causes the low voltage light to come on. and I still have to install a Lx Zeus, Powerflarm and transponder!! Please can you advise how to fix these problems. PeterS