Montgomery Ward has been defunct a long time. That mower may not be a mulching mower - does it have a means of closing off the discharge port? The link came back deleted.

There is no discharge port. Only a square door for bagging attachment, which I do not have.

Okay, it's a mulcher. Is the blade in good condition, sharp, and not on upside down? You can probably find a generic blade for it. The housing has to be clean for mulching. You should probably be cutting at least 3" high. You shouldn't cut wet grass or cut more than 1" of grass at a time.
It may have the wrong blade on it now. If you can find a model number on the mower or a part number on the blade it could go a long way toward getting everything straight on it. Does the existing blade come close to the deck all the way around, maybe about 1/4" clearance? If so, at least the blade is the right size. Does it have airfoils on the back of the blade? If those are worn down, it won't mulch right and the blade should be replaced.

Actually I think that the only thing this will do well is bag. If the area in the rear of the deck keeps filling up with grass, it will clump no matter what. I would look for a bagger at a bone yard and make it fit. Some had rear discharge chutes available. 3.5 or 4 HP engine doesn't make a good mulcher anyways.