I was stating a logical breakdown reason where the boat would not be able to go on either engine. A breakdown I don't find unbelievable as I worked with Navy small craft engines and seen a lot happen to them. I was even on duty one night on one when we were following order by the officer and grounded in Vience, Italy. Hey we told him LOL. He had a compass and a map. We had landmarks, had been on duty all day and remembered them, and were experienced.
If someone high up the Chain of Command in a nation far away in a White Hut had knowingly sent a Navy ship into harms way it would not have been a first. Pueblo was such an incident and LTCDR Boucher was not warned of events in NK and that he was being intercepted by NK waiting on him. His ship was about as well armed as those two boats meaning two 50 cals IIRC. I think LBJ welcomed that incident to deflect from his corruption.
BTW I don't fault Boucher nor his crew for Pueblo because The Pentagon ignored and scoffed at his concerns about carrying Classified material and equipment without a means to to a fast and efficient emergency destruction. You have to have explosives to scuttle post WW2 ships. You can't just flood and sink them and DFM is hard to get to burn on it's own.
I had also considered the possibility of bad fuel, but it just seems unlikely. This whole story is fishy. These people are careful!