In addition to all of the standard things to check with a used rifle(bore,headspace,rust,pitting,cracks,etc),there are a number of other critical wear/breakage points to be checked on a Garand. These include the safety which is liable to break,hammer hooks and nose for breakage/chipping,hammer spring housing for cracks,trigger/sear for chipping/breakage,gas cylinder for internal dimension and external deformation and cracks,gas plug for cracks on the interior face,op rod for piston dimensions and height of the rear tab which engages the receiver,plus correct fit without binding,op rod spring for length,breakage,and deformation,rear sight cover for tension,elevation pinion for excess wear of the "tit" on the interior face,stock fit for fore/aft movement and excess compression of trigger housing bearing surfaces,trigger guard for loose fit/worn lugs,extractor for tension and breakage,bolt for deformation of the firing pin slot at rear,and firing pin for chips and excess wear of the tail which engages the bridge at the rear of the receiver.
You also need to check all of the following which affect timing and function for wear/breakage;clip latch and spring,op rod catch,follower,follower arm,follower rod,follower arm pin,and bullet guide.The receiver itself should be checked for excessive wear on the race which retains the op rod tab,bolt seats,excessive wear on the serrations which engage the elevation pinion, cracks/pits/breakage on the legs,and soundness of the rear bridge.The muzzle should be checked for excessive wear as a result of improper use of a cleaning rod. You can find barrels which appear good and gauge well at the throat,but may have eroded to .303 and greater at the muzzle from cleaning rod wear. In addition to verifying the soundness of individual components,timing must be checked to ensure that the bolt releases at the proper point in the loading process.
Most of these rifles,especially those imported from various third world countries, have been away from competent techical surveillance and maintenance for many years. One pretty safe bet is to buy an ex-Danish rifle. The Danes appear to have exercised good technical control of their rifles and most that I have owned or examined are/were in a safe and functionally acceptable condition.