Hello. I have a shallow well with 2 1/2 horse Mastercraft pumps that look like this

I pump from the well into a 200gal holding tank and from there another pump sends it to the house. All this is in a small building outside the house. It has worked flawlessly for 2 years.
The pump feeding the house had the pressure line to the switch burst which drained the tank and the well and got everything soaked, although most of the water ended up outside.
So, pump to the holding tank needed priming again and thats where I'm at now. I can prime it, it will even self prime sometimes. The well is 18 feet with 6' of water with a foot valve. I can get it into its cycle filling the tank and it looks like it going great. I can watch it for 5 mins and its ok. Then for some reason it just drops pressure, loses prime and I have to do it all over again. Before I do my usual well dance!! (thats the run to the store and buy everything new again) is there something I should be looking at first.
Thanks Mike