The possible ways of water leaking into the power unit are really limited to overfilling of the tub, or cracks in the agitator drive shaft pipe. I also restored a model 30WP which had several cracks in the bronze agitator drive shaft pipe. And of course, water leaked in and ruined the grease in the power unit.
Apparently, the water ingress to the power unit on my Model 32 was done by simply overfilling the tub (probably on numerous occasions.) The bushing on top of the agitator drive post is fairly tight around the drive shaft, so one "overfilling" by mistake wouldn't be enough to cause significant damage. Perhaps the tub was left full of water above the post for an extended period time.
My advice to you when you proceed with removing the tub - do NOT remove the six bronze bolts that hold the tub to the center plate. You only need to remove the three small bolts that hold the center plate to the power unit, which will allow the tub and center plate/agitator post to be removed as one unit. Chances are, you will need to replace the small gasket that goes between the center plate and the power unit (photo attached.)
I've done four restorations on models 30/32 and have never found it necessary to remove the tub from the center plate. It's unnecessary work, unless you noticed a water leak under the tub, which could indicate the center plate gasket has deteriorated, or you wanted to replace the entire center plate/agitator post assembly.
Regarding the Model 30WP with the cracks in the bronze post - since I did not have a replacement center plate and post, I simply covered the cracks with E6000 adhesive. It's quite durable, but does have to be reapplied every couple of years. Short of replacing the post, a better fix would be JB Weld Marine Epoxy, but I haven't done that yet.
