It was leaking prior to the replacement of parts in May, that's what prompted the replacement. It has not been taken apart since then and the install was done carefully. To my knowledge, it did not leak after that replacement until just this weekend but that's hard to say since it's been in storage.
The boot is secure, not off anyway as it is sealed into place and also zip tied to the cable. The only thing I have not done to that boot area is flood the opening where the cable enters the boot with sealant. May try that next.
The screws appear to be fine. By base plate seal, do you mean the O ring on the gear drive?
I think I'm going to look into and install the jack antennae, no moving parts, should be a better seal.