Small Engines (Lawn Mowers, etc.): riding mower wont start, sears craftsman riding mower, craftsman riding mower

Question
I have a sears craftsman riding mower about 4 yrs old. 14 1/2 OHV engine. Never have had any trouble with the engine,; doesn't burn oil, smoke et.. yesterday while mowing in tall grass it acted as if it were about to run out of gas--almost dying, then running then almost dying. So, pulled up to the garage to put more gas in it and found it didn't need any. so tried to start it again and it will not start.At first it made a puttering noise as if it was flooded and trying to start but now just turns over and over but doesn't sound as if it is even trying to catch and start. Gas is fresh, it is getting spark and carb is getting gas. What else should I check? By the way I also need to know how to adjust the clutch/brake as it will keep rolling even when parking brake is applied (has been this way for awhile though).
The only other trouble I have had is the transfer case cracked and had to have it welded back together.
Thankyou sooo much for any help in the matter cause I'm broke! lol!
Cindi
ps the model number is completely worn off but the type is 1255-E3 and says code is 0006152D if that is of any help to you

Answer
It sounds like the running problem is caused by debris in the fuel / carb.  If the engine is revving up and down, this indicates there is a blocked passage inside the carb that will need to be cleaned thoroughly.

There should be an adjustment for the brake shoes on the side of the transmission.  There is usually a shaft that protrudes from the transmission with a brake disc on it.  The brake pads have pressure applied to them via a cammed lever which has an adjustment nut to set the correct amount of slack / tension on the pads.

Hope this helps.