LOL
I'll tell what the tape is for. Do you see the leftmost copper/orange panel ribbon cable. Well the time before last cleaning session, that ribbon cable got sucked into the nozzle of the hoover. It didn't get pulled out or anything but vibrated back and forth in the nozzle at like a million times a second!

Pulled the nozzle away and discovered that one of the tiny wires on the edge of the ribbon cable had been severed. Thought 'Sugar,Sugar,Sugar', I've just destroyed a few thousand pounds worth of equipment. Had a brainwave then and magnetises a needle, picked up a tiny flake of metal from one of the PJ screw heads and finally manouvered it between the ribbon cable sheath after 100 attempts joining the severed ends of the tiny wire. Result!!
Anyway while I had the PJ open this time I put some of the brown tape on the ribbon cable to make sure the flake of metal didn't work its way out while I was working on the PJ.
My first few de-dusting sessions involved just taking off the top cover of the PJ and pointing the airduster into the panel area. I would be lucky to get rid of 50% of the dust. Then I got a little braver and took the Mainboard off which involved disconnecting a few cables and a few screws. That gave me better angles and access with the airduster to the panels but still only from the top so I would still end up with stubborn dust on the bottom of the panels which would still be visible on the screen. Got rid of 80% of the dust with this method.
This last time I decided that by hook or by crook I was stripping the PJ completely. I managed to undo a very stubborn screw that had prevented me taking the PJ apart any further on previous occasions. I had worn away the philips head threads on previous attempts. I was then able to lift the optical block out which gave me access with the air duster to two fans I couldn't access properly before. Gave them a clean aswell as the internal air ducting. With the optical block out I could spray the panels from underneath aswell and was able to completely clear them of dust.
Result was a dust patch free image for the first time ever since I got the PJ and because I cleaned out the fans and ducting my running temps went down too by a significant amount.