Waterpik repair

The battery-powered WP-360 Water Flosser eventually slows down, so I buy another and set the old one aside to fix later. Today is later, to avoid the
infection risk of a shopping trip and the cost of yet another new one. After prying the ribbed ring out with a Swiss Army knife can opener they disassemble easily with a small Phillips. Inside is two tabbed AA NiMH cells, a DC motor and pump, all of which come apart by removing fairly large screws, unlike the tiny ones on another of today's projects.
The on-line repair suggestions are about replacing the battery, but when I took apart an old one for practice the batteries were still charged and the motor had corroded and seized solid. The current, slow one worked fine after I had opened it, which is typical for me. Maybe a bit of clogging dirt was dislodged? I see the same thing with small engine carburetors.
Electrically the 3.17VAC input float-charges the NiMh cells through a series diode. The motor on my good one draws about 1 Amp from a metered power supply, disassembled on the bench without the pump load. The battery voltage dropped from 2.8V (external test charge) to 2.2V before disassembly, 2.5V after.
The motor pinion drives a crown gear with an eccentric for the pump piston. The eccentric might have a trace of factory grease on it. I oiled everything that moves with "safe for plastics" light oil since I didn't find a different suggestion.
Has anyone else fixed one of these with good/bad results?
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Jim Wilkins wrote:

I kept a Braun electric toothbrush working for YEARS past the expected lifetime, with outboard batteries and a drop of oil on each motor bearing every couple years. I'll bet a drop of oil on each end (if you can get to the shaft at both ends) and let it soak in for a few hours will loosen the motor up quite well. Eventually the brushes and or commutator wear away, and that is the end of it.
Jon
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"Jon Elson" wrote in message
Jim Wilkins wrote:

I kept a Braun electric toothbrush working for YEARS past the expected lifetime, with outboard batteries and a drop of oil on each motor bearing every couple years. I'll bet a drop of oil on each end (if you can get to the shaft at both ends) and let it soak in for a few hours will loosen the motor up quite well. Eventually the brushes and or commutator wear away, and that is the end of it.
Jon --------------------------------
I used a needle oiler from a hobby store which reached in past the crown gear and under the pinion. The gear assembly separates from the motor easily but I only did that on the frozen unit because inadequate gear tooth engagement is a reported problem.
I've used turbine oil in a zoom spout bottle on the plain shaft bearings of my megger and found that it needed re-oiling after a year on the shelf, perhaps the thin oil evaporates? The crank drives a planetary speed increaser on a concentric shaft, and becomes stiff if not oiled.
(Amazon.com product link shortened) It's a ripoff of the old Biddle megger. The idea is that if you shock yourself you automatically stop cranking the high voltage generator.
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