As for the direction to drift things in and out of dovetails on Marlins...
Just remember how you load it. Cartridges load into the right side of the receiver, and empties eject from the port on the right side of the receiver. Tap things out (just like the empties) from left to right. Tap things back in (just like you load the rifle) from right to left.
And, for what it is worth... Slip on down to the hardware store and invest in a brass punch and decent dead-blow hammer. Avoid the confrontation with the "ASPCM", as Roe calls it.