Sorry, guess I shouldn't speed read

I just bought the pwc's from a relative, he had purchased them from the original owner about 6 years ago, he is a professional mechanic at kingsland tx. He has well maintained them and they were both running great when I got them july 4 th weekend. I have taken them to the lake before I purchased them several times and had no problems. the only thing I had wrong was the MFD on one wasn't working. Since then The other MFD on the 2nd slt780 quit also. That is my fault though, I swapped the gauges between the two and now neither one work!!! Shouldn't have done that but stuff happens. Both were running fine without the MFD's working, and the one in question run fine until last sunday, rode all day on both, went to load it up and it would not start. Checked the obvious, gas, oil, no water inside (very little) checked connections on cables, wires, etc.... The Slt780 has run fine up until this. Hopes this help with any suggestions on what could have happened and thank's for the tip on ebay for the MFD, I saw the pricetag new and gheesh!! gonna have to sell ALOT of blood for that! ha ha Any help would be greatly appreciated.
Tom.