Does anyone know how to check a second hand machine and how to detect defects, cylinder damages, worn gears, print quality and every tips that would be helpful to know when buying a second hand machine. The machine is a heidelberg SM74 2 colors without perfector.

Thanks

You'll want to see it print on a couple different kinds and weights of stock. Check for fit issues you'll really see it with some fine reverse type. And bring your pressman with you! An experienced guy will notice things about the press that you may not.

I would check the press under running conditions. Also ink up all the cylinders and put on pressure with proper packing.Full ink transfer to all cylinders. Look for any low spots on all cylinders. Also run solids and look for gear marks front to back in color. This will show worn gears. Pulling rollers and checking would be nice but more than likely it would need new rollers. Run some four color on it to with control bars to check for dot slur and fit. Listen for any odd squeaks or strange nosies as it goes on and off pressure. Air leaks, esp. on older Komoris is a big problem. Small air lines and inside on air cylinders is a problem. And also, good luck!