you can't do a quik disconnect with the main drive board eh?
usually there is the laser ribbon that goes from the laser to the logic pcb and then another ribbon or molex type plug that goes to the tray's pcb.
the ribbon has them clamp deals where the molex has actual wire's but can be plugged/unplugged from the logic board
all you need to swap out is your logic board wich is the larger board from your broken drive to the new drive and you should be all set.
dont worry about the tray pcb unless you have eject issue's.
if you have any questions or need help just post'em but worst case if you cannot get it settled I would fix it free just cover the shipping both way's

also when you pull the laser ribbon take it from the laser itseef not the pcb becuase becuase it is attached to the pcb with double sided tape so the ribbon dont get caught in anything and damaged.
the ribbon just plugs into the laser as there is no clamp on them usually but sometimes there is so check to make sure there is no clamp and if not just pull it and it will pull out but if there is clamp make sure you unclamp it or will wont look and hold right if it gets broken.
if you take it off the pcb's side and remove the tape part you risk it getting tangled or damaged by other moving parts.
what I do is take the bottom and top of the drive's casing off flip the drive over pull the laser ribbon from the laser and then unplug the tray pcb from the main logic pcb then there is 2 black plastic prongs on the side's of the pcb pull them to the side lift the board out.
do the same with the other drive then put your old logic board in the new drive attach the molex/ribbons close it up and its good to go.
if you have to solder/desolder on anything what make and model drive do you have and I will look into that model a little better but you should be able to get by with no soldering.
it also makes it easier to get the laser ribbon back in if you manually eject the tray where it is open all the way this raise's the laser and give's you a little more room to work with to get the ribbon back in it's not much but it does help.
there is a bar in the front of the drive that move's left and right if you press it to the side the tray will open if you dont know what I mean just slowly spin the big black gear wheel and you will see the bar move and then know what part I am speaking of.