Urgent Water Pump Problem

Are there any common problems with Shurflo water pumps which stop the water running?

A non-caravanning friend has bought a 10 year old caravan which he intends to live in, in his garden, whilst major building work is carried out on his house following a flood. He has just tried out the water pump and can get nothing more than a dribble coming through either the hot taps or the cold. The pump, which I think is a Shurflo from his description, appears to be running, just no water coming through. Unfortunately, do to the current situation, I can't easily get over to have a look to try to determine the problem. Does anyone have any suggestions that my friend (not particularly practically minded) could check?

What has made it worse is that this building job should have been done just before lock-down which is when he bought the caravan and which only had a three month warranty on it. With the delay in getting the rebuilding work started (starts on Monday next week) the caravan dealer is not being at all helpful as the warranty has now expired.

Any suggestions would be most welcome. Thanks in advance