Basic's: take the top cover off, take the retardment (banana-shaped) out and put it into lighterfluid for 30 minutes to degrease.
Change the lighterfluid once.
Than lubricate the axes with some synthetic oil ( and put it back into it's place.
Check if 1/15 runs OK.
Remount the rest and you are done for a couple of years.
It is helpfull to have a shutter-speed-tester for this.

Congradīs with your new aquisition, you now have a Lego-box for grown-ups as I call my Sinar.