I've recently come across a small grand that seems to have a "simplex" spring and loop action. There is a sticking jack and was wondering if adjusting the grub screw on the front of the jack might solve it. I'm guessing it's to do with spring tensioning but I have to play it for exams next week and don't want to adjust anything if there's a chance of snapping the cord until I have time to take the action out and repair it.
CPL with a small brush will sort a sluggish centre
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