Terry Pinnell Inscribed thus:

I made my Curtain Controller 6 years ago based on a motor I stripped
from an inexpensive battery-operated screwdriver drill (3V). In
general it has worked fine. But for the last year or two it has
developed a strange intermittent fault. Suddenly, instead of opening
or closing the bedroom curtains in under 2 seconds, it will become
glacially slow, taking maybe 10 seconds or so. Although it always gets
there in the end (closing the appropriate microswitch), it's
irritating.

I don't mean 'intermittent' in the usual sense. It continues in this
slow mode for several *months*. Then, just as suddenly, it will revert
to its normal fast mode. And stay that way for months.

A few days ago it once again reverted to slow mode, perhaps the 3rd or
4th
time in 2 or 3 years. I made an even more concerted but fruitless
effort than before to isolate the cause. It's definitely *not* the
batteries, my primary suspect. I've tried several sets of 3 x
NiCd/NiMh C-types, well-charged, all giving identical results. Voltage
during operation remains more than adequate for the 3V motor. I'm also
sure it's not the mechanics, friction, obstruction, etc.

Logically that seems to leave only the motor itself. Is it possible
for such a motor to exhibit this sort of behaviour and if so what's
the likely cause please? Is it fixable or am I going to have to find
an identical motor?

--
Terry, East Grinstead, UK

Grease solidifying with age in the gearbox.

--
Best Regards:
Baron.