Hi, i have an older lowes mower with 12.5 briggs and 38 in deck. i bought it used 6 months ago. I used it to cut my grass 7 or 8 times and it worked just fine until my brother borrowed and ran it low on oil. the piston rod broke. yesterday I raplaced the engine with a 12.5 from a similar lowes mower. i had to jumpthe battery from my car to get it started. it runs fine and the blades engage but the tran wont engage. the clutch doesnt come all the way back in 7th gear like it should. even with the engine off. is the something wrong with the linkage?or is the trans bad? somebody please help. btw. this is my first lawn mower but i am pretty mechanical.