old? style sprocket-type chain tensioner

[pman53]

i have an old maxII. the four chain tensioners are sprockets,not plastic pads.they do not have the typical ratchet teeth which wear out, just one big nut to tighten it with. the two front ones stay put just fine while the back two always eventually loosen up. i am also not sure of the correct routing for the chains with these. any help or pics would be great. also are these tensioners an indication of the age of the machine?

[shorty]

I have a '93 Max VI that has the same setup. If the back tensioners are always coming loose, then check the chain alignment. Chains run under the sprocket, and then sprocket is pressed down against chain to create/control tension. Pressing down on the sprocket teeth can be done with a piece of wood. Lean on it and crank the nut tight.

Hope this helps.