Its definitely not a design fault, they design them like that for a reason
Easiest way is to take it to a reputable mechanic, drain the oil, then remove the oil pressure switch and using a special oil pump that most good mechanics have these days for priming engines(pressurised oil in a old gas bottle) it pumps oil under pressure into the oil galleries. If you have no oil in the sump, the pressure will force the crud back out of the filter screen and into the sump. Of course, now that the crud is loose it will probably find its way back to the oil pickup eventually.
Hence why I would just drop the sump, simpler and faster and you can remove all of the other crud in the sump and check the engine bearings cause no doubt the lack of oil pressure and flow has probably damaged them
