Mystique timing

This is a posting looking for insight, from one professional technician to another. Am working on a 1999 Mystique 2.0 liter, had rough idle and a cam sensor code (PO340). After wasting time with diagnostic routines pinpointing the faulty electronic sensor I returned to basics. I removed the timing covel to find the belt had a 6 inch tear on the long axis and both idler pulleys were damaged, one with a dry bearing while the other was disintegrated. I replaced both pulleys with ford oem parts, and put a goodyear gatorback belt on it. Now I am finding that the belt "walks" off of the cam sprockets about three millimeters, enough to rub on the cover. The cam sensor code is gone now, but I still need to fix the belt problem. The balancer pulley is on, I used factory OTC alignment tools to lock the cams and crank, and dealer technicians I have consulted have not experienced this problem. Car was built in jan of 1999 and has the two idler pulley design, not the one pulley design. Anyone who has experienced and successfully corrected this problem?

Is it hitting up top of the timing cover?

I have seen this before after timing belt replacement..

I would use a shim or a washer under the top bolts to correct this problem as that is the only thing that I could come up with..

Good Luck!!!!!!!

Hi!
Here is my problem description and solving.
I have Mercury Mystique 98, 4 cyl (2.0L) equipped with Zetec engine.
I bought it half a year ago with mileage of 111 kmiles. Previous timing belt was not too bad but needed to be replaced soon.
I have replaced timing belt recently. After that before putting the covers on I found out that the belt have a tendency to slip off the camshaft sprockets. In spite of this I closed the covers and drove only 60 miles or so. Then my engine stopped because the belt weakened and the exhaust camshaft turned about half a turn but the belt did not slip off completely. When I unbolted the covers I found out that half of it width was damaged and almost cut off. I installed new timing belt, tensioner and both idler pulleys. When I check it again and the belt was slipping in the same manner as first time even I gad set the correct tension and torque. I have decided then put a piece of flat metal foil between the tensioner and the engine body (half of the area of the tensioner washer in direction out of the engine) glued it with epoxy. The foil thickness was 0.2 mm. After that I have tested the engine again before installing the covers. The belt was OK. To be precise it was moving slightly out off the engine at high acceleration (5000 rpm) and towards the engine a little at idling speed. But it was stable and did not come to the edges of the sprockets. I think the reason there was either hole of the tensioner which is not perpendicular to the engine for the or slightly bent camshafts. I am really in doubts about the last because it is not easy to bend the camshafts. The car ran about 100 miles and checked the belt. It was OK. Now I am keep testing this stuff.
Here is my experience. Did anybody have such a bad experience with the Zetec engine? Did you have any problems during the warranty period?

Alex