How to open an Aqualung Legend 2nd stage

[TheHuth]

I have an older Aqualung Legend. I need to peak inside to see if it needs to be cleaned, or if it needs parts to be replaced. I cant figure out how to pop it open. I dont want to apply elbow grease unless I know where to put the pressure; otherwise I might break it. Anyone got simple directions?

 

[uncfnp]

Is it this one? Uses a pin spanner.

http://scubaspares.com/manuals/LXLSS.pdf.