If the steering has play, usually that can be fixed doing adjustments. My old JD850 had 6-inches of excessive play. It reminded me of an old Ford 8N. The JD850 (Yanmar YM2500/YM2610) could be adjusted to corrected for that issue.
Yes, the blow-by can be something to monitor.
Examine the fuel filter and notice and weeping around the filter seal.
Before starting the tractor up, pop the hood and squeeze the radiator hoses. If they feel soft, then they have aged and weakened from the inside. Look for any residue of diesel, glycol or oil anywhere on the tractor. Check the belts and gauges. Verify that the thermostart functions (cold temp heating for the fuel). Like others said, check the brakes. It you can check the 3-pt lift with an attachment to ensure it rises normally and lowers without getting hung up nor mowing too slowly. Look for any white foamy stuff in the oil pan or cap, and none either in the hydraulics.
OK I'm out of ideas otherwise at this moment.