Chain stretch question 560sl.

[JBoggs]

I took the drivers side valve cover loose to check the rails and I have a question about what I found. Both rails are intact and look relatively new-still mostly white color so they have been changed on schedule (205k mile car). Previous owner changed the chain and rails at 90k I think.

I did notice that when I played with the chain it appears to have a lot of slack in. In other words, I could pick the chain up off the outside rail and lift it 1/2 to maybe even a full inch. For perspective I suppose I could have fit the handle of my 3/8 socket between the rail and the chain.

The other day, I pulled the passengers valve cover, set it on TDC and read the damper and it didn't show more than 2 degrees off from the damper. I did notice that when I rotated the damper counter clockwise by hand, that there appeared to be sevaral degrees of play. (I only turned it a slight bit until I got resistance to see what would happen)

This is all new to me so maybe I thought my chain hadn't stretched by the numbers but the slack tells me that I should replace the chain. In other words, should it be pretty tight all the way round or a little play is OK?

Thanks.

J. Boggs