[R-390] Kilocycle knob moves megacycle change knob

[Dan Merz]

Jacques, thanks for suggestion. The problem was solved by lubrication of the sliding racks and some exercising of the mechanism. I got some off-post suggestions from Roger R. and I'm copying you on details of my use of his suggestions.  I'll lightly re-lube the gears but that's beyond what was needed.  Reducing friction there can't hurt though the KC knob turns pretty easily and the MC knob is holding ok at the detent position after I lubed the racks. 
Comments to Roger
I needed a little perspective before going off the deep end. I see the detent mechanism and realize with your comments and after looking at the set on the bench what is going on. I'm pursuing that some re-lubrication will solve the problem. The differential gear can throw KC motion back on the MC knob if the detent isn't holding strong enough relative to friction of gears on the other path for motion. I'm thinking lubrication of the path of gearing and the sliding racks beyond the differential will take care of it. The detent almost reliably holds now  after I played with the motion a bit so I think lubrication will do it without messing with the detent mechanism. It took me a while to see where the detent is but finally was sure when I i.d'd it in chapters 6 and 10 of the 21st century manual.

 Best regards, Dan
Sent from my iPad Air2

> On Apr 3, 2017, at 12:20 PM, Jacques Fortin <jacques.f at videotron.ca> wrote:
> 
> The differential drive is frozen ?
> 
> 73, Jacques, VE2JFE
> 
> -----Message d'origine-----
> De : R-390 [mailto:r-390-bounces at mailman.qth.net] De la part de Dan Merz
> Envoyé : 3 avril 2017 14:59
> À : r-390 at mailman.qth.net
> Objet : [R-390] Kilocycle knob moves megacycle change knob
> 
> Hi, my 390a has symptom that moving the kilocycle knob also moves the
> megacycle change knob. I haven't explored yet but it seems megacycle knob
> itself is "gummy" and not working right so I haven't forced it much. This
> receiver hasn't been used much in last 10 years but was working smoothly
> probably a year ago. And had been cleaned and lubed with synthetic oil,
> maybe 15 years ago. I suspect some shaft is sticking to cause this odd
> symptom.  Where to look first?
> 
> Sent from my iPad Air2
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