Having convinced myself the ball had something to do with proximity detection, it didn’t enter my head that it could be a simple seal. Thanks for the idea Jason and others.

As for that hole being part of the filling process, I need to point out that …

1. The 2mm ball blocks a through-hole of about 1.5mm diameter,
2. The pump is lowered into the fluid cartridge down a hole about 29mm diameter,
3. The drain (or return) hole in the cartridge is about 13mm diameter,
4. The two holes are initially closed by a separate lid moulding heat staked in three places,
5. The stakes are deliberately friable allowing removal and disposal of the lid,
6. U/S or vibration welding was likely used for joining/sealing the base and top,
7. The shaver is not involved when installing the cleaner cartridge.

Assuming the steel ball is not for detection, the hole it blocks is rather small for filling. With larger holes 2, and 3, available for filling, the 1.5mm hole (into which the ball has been pressed), may be an air vent rather than a filling point.

Given that heat staking and welding were a part of assembly, I would assume the 1.5mm (vent?) hole could be closed by heat swaging.

The cleaning device has the ability to determine the presence or otherwise of (sufficient) fluid. Having now destroyed the cartridge and a new one lasting for at least three months, further investigation will have to wait.

Thank for your interest and comments,

Sam

PS – A cursory scan of the Internet failed to disclose the method of manufacture.

Edited By Sam Stones on 16/04/2021 03:27:43