I had a Juno-106 come into the shop recently, and it had a couple of common issues: the classic chorus tick and some dying voices. I pulled the board to take a look.
The through-hole tantalums on the power rails were the culprits – two of them had gone leaky. I replaced all six of those with film caps. While I was in there, I also reflowed the chorus BBD socket.
After those fixes, it powered up clean, and the chorus is silent now.