noodlerooney

When the clutch is engaged, the belt alignment should be fairly close. A belt width is not close. There are several sets of mounting holes in the top of the engine deck for various engines. The set of holes for the 318cc Tecumseh engines is exactly the same as that for the Tecumseh 358cc OHV except it is forward by about  .220". My guess is that the engine and mounting straps were placed into the wrong set of holes (11.5hp engine in the 13hp holes). These holes overlap some and connect kinda like a figure 8. This is rare but I've seen it a few times. I have pictures where you can identify whether the engine is in the right postion or not without removing the engine, but won't be able to get them to you until tomorrow. You could remove the belts and unbolt the engine, lift it up a bit and check whether the engine straps are in the front or the rear of the figure 8 slot. You could also measure some reference points (frame feature versus engine base) and compare them to another unit to see if they are different. If they are in the wrong position you can remove the engine and move the bolt straps forward. You can use a hammer and screwdriver to push the rivet forward in the slot, then re-mount the engine. Let me know if this is not the problem.

PK