How do I open my Philips Power Flosser 7000, to fix an internal leak?

I spent a couple of more hours on trying to repair my Philips Power Flosser 7000. What I found out may be useful to others. I discovered that in addition to the two visible screws on the bottom of the device, there are two more screws that are hidden by two of the rubber feet. I was able to pry these feet partly up, using a small straight-blade screwdriver. I pried from the end of each foot closer to the centerline of the device, to reveal the hidden screws. I didn't have to take the feet completely off. These four bottom screws all require a Torx T-8 driver. While I removed these screws using a short T-8 bit in a magnetic multi-tip screwdriver, some later screws required a slender, dedicated T-8 driver.

Removing these four screws didn't get me very far into the device. All the important parts are inside the white rigid plastic squashed cylinder that makes up the main part of the case. I removed the flossing intensity control knob by pulling it outward with my fingers. For re-attaching it later, align the flat spot on the center rod, and push it back in. This knob has no stops– you can spin it indefinitely in either direction.

I next removed the two screws that hold the coiled tubing and handpiece to the flosser. These screws will take a Phillips or straight blade screwdriver. Removing the coiled tubing, I could see a small O-ring at the connection point, that had been pinched during assembly, and didn't provide a reliable seal. I replaced the O-ring, and it diminished the leak by a small amount. Another leak remained.

The coiled tubing described above screws into a small, rectangular piece of plastic with rounded corners. That piece snaps into the Flosser case from the outside! However, it is attached to the inner Flosser pump by semi-rigid plastic tubing, which I couldn't remove from the connections. I was eventually able to snap this rectangular piece of plastic outward, twist it so that it could go through its hole at an angle, and maneuver it into the inside of the case.

Next, I removed the six T-8 screws that held on the top of the case, using a slender, dedicated T-8 driver. This allowed removing the internal working parts– the motor, tubing, and electronics. The switches on the outside of the case and not connected to the inside electronics. They function by pushing against the internal parts, so they can be ignored during disassembly and reassembly.

There are two water tubes inside the case, each a possible source of the leaks. One is a translucent, flexible tube that leads from the water reservoir to the pump. This tube may be made of silicone, and is about 10mm outside diameter. The second tube is made of an opaque, white plastic, ~3mm OD, with limited flexibility. This plastic has to handle the high-pressure pulses of the flosser. (It is the same kind of tubing that forms the coil connecting the flosser to the handpiece.) I put the water reservoir on top of the internal parts, and I could see water dripping at a quick rate from where the 3mm tubing connected into some kind of a plastic junction box. This was the main leak that I needed to fix.

This second tube fits a rectangular piece of plastic, which is connected to the pump's junction box by two T-8 screws. I removed these two screws, and pried the top piece off, with its connected tubing, using my pocket knife. Inside was a blue O-ring and a metal baffle. I suspected that the O-ring was the cause of the leak. However, it looked like it was in good shape, and I didn't have a replacement of the correct size. I put a little silicone grease on it, and reassembled the junction box, carefully tightening the two screws.

I refilled the reservoir again, and found that there was no leak. However, I was skeptical that I had fixed the problem. I reassembled the flosser, so that I could try it under power. After turning it on, water leaked out the bottom, as before. I suspect that the blue O-ring is not creating a good enough seal when the pump builds up pressure. My next step will be replacing this blue O-ring.

I will try that on another day. Overall, disassembly is tedious, but doable, if you have a slender T-8 screwdriver, a regular Phillips, and a small straight-blade screwdriver. Replacing the two different-size O-rings may solve the leaking problem, but that remains to be verified.