I have seen many many posts on this thread AND NOW I KNOW WHY!! ;-)
I was working with my (new to me) 7603 with 18 and 18A plugins, when ALL OF A SUDDEN, the vertical range selector knob BROKE IN HALF... HUH! Upon close observation, I find that the knobs on my 18 (and my 18A!) have been re-glued, some more than once! So, out came the juice/solvent/glue bottle and now there is a knob laying on the bench glued and wrapped; hoping for a better day.
Of course, I went to "sphere.bc.ca/test/tek-parts/tek-knobs.html" to find some replacements... only to find the vertical range selector knobs are out of stock, BUT when they were in stock they were $10.00 each! Whoa...
Thank you to those members who are actively searching for a method of manufacturing replacement knobs! I now understand the push to get something working... I wish I could help, but I am really out of my element when it comes to creation of things. Breaking them is probably the only thing I am good at, these days.
What would you say if I have an urge to put some lube into the switch assemblies in my plugins, to lower the torque needed to turn them? Thoughts?
Thanks for listening,