You don't say what model you have. Are parts still readily available? I loved those LB smokers, simple, reliable and easy to service but they are a thing of the past.
The Toro Super Recycler is a premium mower especially if you are into mulching.The current LB and Toro Recycler are more entry level still decent but not up to the standard of the LB aluminum staggered wheel.

If your current lawnmower otherwise does the job, is in good condition and the repair costs less than the price of a new lawn mower then it would make sense to simply repair.