Ron's page here is an interesting read https://www.sw-em.com/Timing%20Gear%20Notes.htm
Page has this link to a long thread about my timing gear failure and repair, with pics and links to Youtube about it.

https://www.volvoforums.org.uk/showthread.php?t=250654&highlight=Timing+gear


If you can rent the cam gear refitting tool from Erik I would recommend it. Don't try and hammer it on as you can knock the plug out of the back of the block and that will mean gearbox and bell housing out to replace it. Problem made worse is you won't know it's out until you get lots of oil leaking out of the back of the block and onto the clutch. Also do not try and wind the gear on with the cam nut as this can break the nose off the cam if the gear gets stuck.

Note the reduced torque setting for the nut and use of Loctite.

Good luck, I hope the job goes well.