Pa

I have a problem with a 973 older model when warm moves very slow.The rite track seems strong on turns but the left is dead when sitting at an idle i hear a surging from the trany and a thud like sound from left track .im thinking a bad track motor . i removed the top cover from the trany and linkage on livers on the inside are sloppy for the brakes. also when i bring rpm of engine up half throttle oil is almost like spitting up from left side under the valve with the large spring around it . can any one help with this problem.