The clicking comes from the laser lens, moved back and forth, hitting the end stops in an attempt to find the focus point. This is the symptoms that so many repairers diagnose as a bad laser and, admittently, it looks like exactly that but it's not ! It's the spindle motor that is at fault. It runs, yes, and if you rotate it by hand it seems to run freely, just not freely enough. You will notice the difference after the repair. Of course, the laser LED could be faulty, I've just never seen one that was yet, and I've seen many CD50's.
There's a hex grub screw at the side of the CD clamp. Note the position of the clamp (distance from the base) or you will have to adjust it later using trial and error and CD's of different thickness. The service manual gives a firm measurement but I've found it to be useless in practice.
And do be careful when you press the motor apart. The housing distorts easily and the magnets inside are brittle. Notice the axial play it has before disassembling and try to obtain the same when pressing it back together.
There is a number of silicon washers inside and outside of the motor, take a note of how many and which ones goes where.
Martin