There's a strip up the back holding on the grill material. That's the first place to look before giving up trying to dismantle these.
Well the TW-1 and 1a are a bit different. The 1 is positioned with dowels and then glued. By now the glue is dried and brittle, so it's easier to knock loose. Do not twist the Model 1 (non-A)...
Since the sound of these is highly dependent on the properties of the (1/4 wave ish or TL ish) cabinets, when you put them back together seal every joint, and do both cabs exactly the same for best imaging. Read up on 1/4 wave and TL. Are you a perfectionist like Monk? Good. You have measuring software, mikes, and patience? Good.
Be sure to check polarity etc. Might not want to open em up a second time for a minor glitch.