I would like to buy replacement wheels (2 sets) for my YC-500 Flowtron handy hauler yard cart.

You question is very vague as to what type of push cart your needing wheels for.

Taking a guess your describing a 3-wheel GOLF push cart, this site sells replacement parts. (If not a golf cart, please post a new question describing the make and model of cart).

https://news.sunmountain.com/golf-push-pull-cart-parts/

Copy following link to identify timer and download possible manual:
http://waterheatertimer.org/Woods-timers-and-manuals.html#outdoor

These household-type timers have 1 year limited warranty. Sometimes they last for a few months, or stop after 1 year, and occasionally they last longer 3-4 years.

Solution:
Buy another yard stake, or plug-in timer:
Example in-wall timer: Woods 49650-59204 at my house.
http://waterheatertimer.org/images/IMG_2060-woods-59204.jpg

Another handy thing is the Woods 32555 remote control. Let's you turn on outdoor lights from inside the car, or inside the home.
http://waterheatertimer.org/images/Woods-3255-image-500.jpg

Each item above is sold at Amazon, or local home center or hardware, or box store Sears-Target-etc

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

I would look in the local phone book.

http://www.ehow.com/how_5932676_tow-front-wheel-drive.html

Simple Google search for Flowtron LE-900 manual, right on Flowtron.com site. For more help, just contact Flotron: http://www.flowtron.com/mm5/merchant.mvc?Screen=CU&Store_Code=F

I’m happy to help further over the phone at https://www.6ya.com/expert/donald_f2ed37026a3ac881

The screw is a common one, Make sure it is at least a grade 5 or grade 8. The o-ring may be another matter, but should be available at hardware and most definitely a hydraulic hose shop would have it.

Go to www.flowtron.com. There you can find the parts you are looking for like ler-500 spinner assembly for $20.95.
Good Day.

I have an electric weedwacker which may be different. In the leaf wacker there are four small holes very near the center screw on the revolving shaft. These holes form two small tunnels. cut two pieces of line (10-12 inches) and stick one through each tunnel. Center each line, put the two ends together and poke them out through the small hole on the edge of the rotating shaft. You end up with two sets of plastic line facing out from the central shaft. Flowtron may be different. Good luck.

I was able to get a replacement 5 amp MB-1 push to reset circuit breaker for my Flowtron LE-900 directly from Snap Action http://snapaction.net/ for no replacement cost and no shipping/handling cost. No one at Snap Action enquired as to what it was for, age, warranty, etc. (their MB1 product description indicates it to have a lifetime guarantee). I just had to mail them the defective original breaker - took about 2 weeks to receive the replacement.

Brett