"Adjustment of 700/900 D24 Diesel Injection Pump. [John Davies] The diesel injector pump is adjusted with two standard tools - a U shaped bar to fit the camshaft, and a metal plug to fit the pump. Once the camshaft is aligned to the bottom pulley(vibration damper), place the plug through the pump sprocket into the pump bracket, and then fit the rear sprocket to the cam, and fit the belt all as per the green book.
Then - and this is the bit I wish someone had told me - pull backwards gently on the belt a little against the pump spring until the plug is an easy fit - i.e. easily moveable with the fingertips - and tighten sprocket still holding belt in the same position. Once tight it should be possible to remove plug easily. If not your timing may not be quite correct, so just try again. .
Even the small amount of tension caused by the pump exerting pressure against the plug seems to affect the pump timing quite substantially - it represents about 3mm - 4mm on the outer edge of the sprocket. It doesn't sound important but it is - since learning to simply tension the belt in this way doing this I have discovered to my delight I no longer have to fine tune the pump with a clock gauge.
Just to clarify, I do not using the sprocket holding tool initially but pull back on the belt with one hand, check the plug, tighten the sprocket just a little more than finger tight with a spanner, check plug again, remove plug if satisfactory and then tighten sprocket fully with the sprocket holding tool. This makes it a one person job"
I found this on another forum, I'll maybe try it with the 11mm socket tip.