Adjusting Valve Shims

[Chambers]

Hi all, I have pinpointed a ticking sound coming from the exhaust side cam, cylinder three or four. I have looked though the Haynes and it shows that you need a special tool to assist in the removal of the shims. I was wondering if anyone has done this, and has anyone ever had to replace the shims?

Now I haven't had a chance to take the valve cover off to actually see if it is the shim ticking, but I can't see it being much else in that area. Any ideas, suggestions, or help would be great, Thanks.