Been there some years ago.
The first thing I was told to do was to buy a conductive pen like this one.
| | | | Silver Conductive Pen, Silver Flex Conductive Pen, Nickel Conductive Pen - Intertronics CircuitWorks® Conductive Pen makes instant conductive traces on circuit boards, available in silver, silver flex, and nickel conductive pen options. | | | |
They are expensive but worth it. There are cheap ones but they don't do the work.
With this pen you can retrace every single line in the FSR and the keys will magicly start to work.
Probably even the "malfunctioning" octave is just the ground connection that need some retracing.
To verify this, just connect another octave to that "malfunctioning" octave multipin socket to see if it's the FSR or other board issue.
This method will put every single "key" working but sensivity will never be 100% like new.
One other important issue is the FSRs connector plug that connects to the board.
Since it's "stapled" to the the FSR it's very very unstable.
After a lot of work I managed to find the name for the plug and buy new.
I can't recall how many pins that FSRs are. Check it out. If you can't find the exact number of pins buy one with more pins, it will fit on the board.
Some years ago a guy was selling like brand new FSRs for the sillicon mallet. I bought 3 just in case but he said he had like a dozen of them.
| | | | 3 Simmons Silicon Mallet FSRs | eBay 3 Simmons Silicon Mallet FSRs | Musical Instruments & Gear, Percussion, Drums | eBay! | | | |
Contact the seller on that page and check with him if he still has anything related.
Hope it helps.