Pump at the cistern defective? Experiences?

Good day,

Recently my cistern pump has stopped working. It started with irregular pumping. Sometimes it worked, sometimes it didn’t.
So I took the pump out of the cistern and cleaned it roughly; you can’t just easily unscrew it.
Then put it back in, and then the problem was that the fuse always blew when I plugged it in.
So I took it out again, waited about a week, and put the thing back in. Now the fuse doesn’t blow anymore, but no water is being pumped either.

It is the following pump: Umbra Pompe Acuafluss.
The pump just lies in the water, is plugged in, and when the tap is turned on, it must pump water.

Nice campfire story… but what question do you have?

If this pump simply lies in the cistern, then you have operated it horizontally. This type of well pump is not designed for that. Buy a suitable pump and you will have peace for years.

Well, if anyone has any idea what this could be caused by, I thought this was self-explanatory ;)
According to the manual, the pump can be operated both upright and lying down.

If the pump no longer works, the pressure switch is installed in the pump, it cannot be opened, you are obviously not a professional, and the fuse also blows, it is high time to dispose of the pump…

The pump can already be opened, just not that easily. Since this is apparently not desired by the manufacturer, I thought I would first ask here if anyone knows the problem and was able to fix it easily before I disassemble it.