"Steve" wrote in message
...
Al,
My SP-600 has both problems....slippage AND backlash.
I did see how the brass on brass friction drive is done at
the
tapered brass wheels and the dials. I tried everything to
eliminate
the slippage, and was 95% succesful.

I've come to the conclusion that this radio has been used
a LOT,
and is just showing signs of excessive wear. The front
panel
had never been off, so I'm sure the bearing at the front
of
the tuning cap is still there, but I'll bet its corroded
to some
degree. Everything else on this radio was. I even replaced
most of the screws because they were so rusty. I'll pull
out
the bearing tomorrow and take a look.

The tuning mechanism on the SP-600 is normally silky
smooth,
and certainly one of the reasons I've always enjoyed using
them
over the years.

Thanks very much for your note and suggestions!

Steve

Another although unlikely possibility is that the clamp
for the bandspread dial, which drives the rest of the
mechinism, is not tight. The symptom is that the logging
dial turns but the main dial does not. That doesn't sound
like what you describe.
The times I've had slippage have all been caused by
residue of some sort on the edge of the logging dial and the
friction wheels which drive it, they must be absolutely
clean and dry.
I've also seen one case where the movement of the spring
loaded "spiders" was limited because of MFP compound, the
spiders must move very freely.
There is a pretty extensive handbook showing the gear
mechanism on the BAMA site. It should be absolutely buttery
smooth.


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Richard Knoppow
Los Angeles, CA, USA