I'm not sure it's with age,there just soooooo thin,and there isn't any bolt holes to put a pulley on.Which is how I usually do them.You just make sure you look after that mower as well.If not send it my way.I haven't been lucky enough to find one yet.I have the two stroke version.Just like the four stroke one they would look great sitting next to each other.Best of luck with your search I'm trying to find one as well.

Here for a good time,not a long time.