Funny you mention your B3. My good friend an I were just ripping some old Deep Purple tunes TODAY and reminiscing about Jon Lord's classic B3 - C3 rock organ tone. That was such a great sound!
It's actually a 1952 Hammond B2 that has been fitted with Trek II percussion (which is dangling down under the right side) I also have a direct out which goes straight into an amp for that "John Lord" sound (God rest his soul).
Need to spin up those tonewheels every year or so -- just like your old hard drives.
Check the tonewheel oil and lube the starter motor and pinion gear before firing it up -- some didn't have a lube point on the starter motor.
The B2, like the BV / Trek2 I carried on the road throughout the seventies had a darker sound than the B3; but with the Trek it sounded great through the 147.