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Cueing problem solved. Here’s what I learned. (long)

Firstly, it’s useful to know how the mechanism works. My mechanism, and apparently most others, depend upon the stickiness of a special thick silicone smeared between a plug and the cylinder it slides in. In my case, there are circumferential grooves in the plug which act as a small reservoir for the silicone. The plug is raised by a camshaft attached to the cueing lever and driven slowly back down by a spring when the cueing lever is lowered. A rod sticks up from the plug and the arm support is attached to the top of the rod. For the mechanism to work properly it is important that the space above and below the plug are vented or trapped air will act as a spring and prevent proper operation. In my mechanism, air above the plug enters and leaves through the oversized holes for the central rod and a sliding locator pin that keeps the arm support pointed in the right direction. Air below the plug enters and leaves through the clearance space around the cam shaft.
My original problem was caused by silicone finding its way down to the camshaft and forming an unintended seal. This trapped air which stopped the piston from dropping completely and causing it to rebound if it was pressed down. I could have solved the problem in 10 minutes by pulling out the camshaft cleaning it and the hole it fits through and reassembling. Way too easy!!
If you need to replace the silicone it seems that substitutes will not do. This is based on advice from “No Transistors” and from Rob, the local tech who supplied me with the needed drop of silicone. Rob told me that he unsuccessfully tried all kinds of substitutes before ordering from “needledoctor”. You can also get the necessary stuff in small quantities at “turntablebasics” in a variety of viscosities and very likely at other places. I’m not sure what the viscosity of the stuff I used is but its very slow flowing.
Use it very sparingly. When I first tried it I put in too much. The plug would barely move and the surplus resealed the bottom vent. After I re-cleaned the camshaft area and removed the excess from the cylinder and plug, everything worked fine.
Thanks to all
David



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  • Cueing problem solved. Here’s what I learned. (long) - energyandair 01/26/0521:20:33 01/26/05 (0)


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