88 Ram 50 Idler Pulley Failure

I'm fooling with my neighbor's 1988 Ram 50 with the 2.0 liter Mitsu engine. Upon removing the timing belt cover, ball bearings fell over the floor.
There are 2 belts under there. The main timing belt and pulleys are ok. There is a smaller toothed belt between the crank and what I assume is the oil pump. The idler pulley between them is what is toast.
Now, if this second belt runs the oil pump like I think, why is there a timing mark on the sprocket? This is what's leading me to think it might not be the oil pump. If not, what is it, and how critical is the mark? Is there probable damage if the the motor was running (it was) with a completely disintegrated idler pulley?
Thanks a bunch, all.
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engine.
Thats a counter balance shaft...it rides in oil, altho its no pump.

Is
If you get it out of time, it can be real fun to try to figure out why its seeming to miss like hell all the time.... Make SURE you get it back in time right. Its been so damn long since I did one that I suggest you do what we would do....get a manual, or a chiltons, etc..and get the mark positions CORRECT.

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Thanks. Then it appears we've found why it was running rough. I was baffled because the main belt is ok, as were the plugs, cap rotor, etc. I thought I would still have to diagnose that after the new pulley arrives. I'll treat it as good news. And, I'm assuming no damage running it off a few teeth, just rough running. More good news.
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ok.
might
its
did
chiltons,
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I doubt I'll see the innards of the thing. I still don't know what the balance shaft is for and how it affects the crappy running condition. I've not seen anything like this on the Honda, Volvo or VW 4-cyl engines I've worked on.
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arrives.
a
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Makes sense. I meant "old" Hondas, Volvos, and VWs. :)
Thanks again, all. I believe I have what I need to resurect our neighborhood oversized wheelbarrow.
Scott
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