Green Green Business

My Bissell Big Green Clean Machine of 10 yrs. has low suction yet motor is fine. Tubes are clear, motor rpm fine. No air leaks anywhere. I think the impeller may be fouled with fiber or dog hair. How then to open the stupid power unit? There are 4 holes in the gray plastic module, deep welled to ensure the poor customer great difficulty opening it, forcing you to get it "serviced" for megabucks. Shining flashlight down a hole I see a metalic "something" like a rivet..not a slot or phillips screw, allen, hex bolt etc.. How do I open that power unit? I don’t want to pay some cluck 35 bucks to clean dog hair out of an impeller.
RE: the suggestiong to visit the FAQ link on www.bissell.com, FAQ didn’t have any info on disassembly of the power unit. I think Bissell wants to make more $$ by their service techies cleaning out impeller fans rather than actually help a client who lives literally in a 3rd world country WITH NO TECHIES and NO PARTS to fix their machine. I tried the FAQ den before I posted this question. Thanks anyway..anyone have the correct answer? Thanks
I called a repairman, together disassembled the power unit. Doesen’t screw together, it pops apart held by 4 plastic clips inside. A medium flat screwdriver pries out & up the green parton from the green half to loosen the clips underneath. Careful, might break it if too much force. Once apart the fan outlets were plugged w/ dog hair. Taking the metal unit out first was a trick, then we took apart the 2 part metal "can" (has 2 sections) by forcebly prying it open, partially bending the rims (which we hammered back into shape before reassembly). 10 years of gunk & dog hair…reassembled the can halves, then the rest. paid BUT I WATCHED. Dog hair got there because wifey didn’t use the removable disklike sponge filter (which she lost) & flotsom stuck in the port in the exit of the power unit summarily clogging the exit vents which are small..1/8th inch by 1/2 inch. MORAL: USE THAT ROUND DISKLIKE SPONGE FILTER ALWAYS. If you lose it make another out of similar sponge.