I have thought about the filter mod. I'm a bit reluctant to drill into the housing, as there were also some stories that said it wasn't very successful.
When you say the filter at the bottom, that's the low pressure filter? Could it be that it's only that one that's clogged?
I still have to open the tank, take the pump out and look inside.
Does the hole need to be drilled into that sealed unit? In other words, if I mess up I need to replace that part?