I need to replace the camshaft on my 81 240D and while looking over the instructions in the Haynes manual, I become a little concerned about how to remove the camshaft sprocket. The manual says in classic Haynes vagueness: "Remove sprocket and washer and use a piece of wire to hold tension on the timing chain"; however the method used to hold back the chain in the accompanying photo appears like it would be very easy to allow the chain to slip off either the crank or the IP. I was just wondering if anyone had done this before and had some pointers on the best way to go about it.

__________________
'95 Geo Metro 3-cyl 5-speed
'97 Geo Metro 3-cyl 5-speed x2
'81 Mercedes 240D 4-speed manual RIP