hi there<br />if any has any ideas on how to fix this problem it would be a great help. Motor info:<br />850 Thunderbolt Blue Band Merc Eng No. 4366928. 4 coil electronic ignition NO DISTRIBUTOR<br />This engine is only running on 3 cyc. I've test all the cyc for spark and found no. 3 has no spark at all. Yesterday after going about 300metres in the boat it lost a lot of power. On the way back the cyc would kick in for a second then drop out again. It now seems to have fully dropped out. I've re-wired all connections from the switch box to the coils because the wires were very old and corroded. I've swapped the coild and leads around the found they are all working fine. I'm assuming this problem is coming from within the switch box because all the other cyc have spark. Is there anything else I can check? If the problem was behind the switch box the other cyc would spark or fire...? But they all do so I'm assuming the problem is associated with the switch box. I've priced a new on on the net and they are very expensive so i was wondering if i could take the old one somewhere for repair or at least test it to make sure that is my problem. Any help anyone can offer would be great. Thanks Nial.<br />PS - I just purchased 4 new coils for this engine about 2 months ago and I noticed when I pulled them out to swap them around the grey magnet looking piece on the outside of some of them was cracked? Shouls this happen so quickly and will it be a problem in the future.