Given the possible consequences, I would pull both mags and have then
looked over. Why? As you said, you risk a failure away from home at an
inconvenient place and time (at night, on Sunday, on a field with no FBO).

Why both? If you have another year to go before overhaul time (which I
trust you are doing every 500 hours), and one is flaky, there is a
chance that whoever did them last time was less that perfect.

But, that's just me. I take both Slicks in every 400-500 hours. We
usually wind up replacing one and overhauling the other. The next time
around, the new one gets overhauled and the overhauled one gets
replaced. Usually costs around $550 or so. Cheap piece of mind for me.

I have no experience with Bendix mags. So, if you have them, others will
need to chime in.

Good Luck,
Mike

He noticed that the impulse coupler on the left mag wasn't
clicking. He turned it a little faster and it works fine. Tried it slow again and sometimes... no clicky. Since
I've had no starting problems, he suggests I just keep flying it unless it begins to give trouble. The mags won't be
due for overhaul for at least another year. My question is: Is there a slow death type "normal" failure mode in
which progressively harder starts occur or do impulse couplers usually fail suddenly and leave you stranded? I
really don't want to throw away money. On the other hand I'd rather not get stranded after dark at an airport away
from home with no mechanics around or parts to be had.