The front wheels wobble on my Toro Z - Master 597D lawn mower. How do I stop it

Toro TimeMaster 20199 Operator Manual

Pdf manual for models 20199 and 20200 30" mowers.
Hope this helps you out

Remove plastic cover on front of machine. This will give you a visual on your belt and pulley attached to the transmission. It may be the belt. Check for cracking or glazing on the inside of the belt. You can also try turning the pulley by hand if it is stuck or wobbly then your transmission is junk. Hope this helps you.

Replace drive cable

check the cable at the front gear box

I have a 22" Toro Recycler Lawn Mower with front wheel drive. After many years the original tires wore out, primarily the left front.
After I replaced the wheels the front wheels kept falling off. I learned that Toro uses an unusual two layer washer on the front wheels. You need a) either an exact replacement for this washer OR b) two separate washers. The hole of the washer is 3/8" Everbilt has the smaller flat washer PN 637-009 and the larger washer can be found in the Everbilt PN 281-293. The SMALLER washer must be placed closer to the frame, the larger washer is closer to the wheel. Once this was done it ran perfectly.
Later I found pieces of the original washers in the grass. Toro had the replacement washer available on their website, I was just in a hurry to get the mower back up and running. The Everbilt washers were purchased at Home Depot.

The transmissions gear is bad need to replace

Remove the left wheel and check the gears inside the wheel and the drive sheft. They might be worn or sheared and need renewing or maybe they just need oiling. Spray them with WD 40.

Unplug the spark plug and check under the deck. Check for blade wobble and tighten. Another possible cause is the gearing for the drive wheels. Make sure wheels are secure.

Removed all the debris that had wound around the front wheels and it works again. Thanks for the help.

look to see if the belt can off or broke... good luck.