The main landing gear strut is locked into the down position using a drag strut.  The drag strut bolts to the airframe on tabs welded to a U-bracket located on the bottom of the rear wing spar.  This U-bracket is installed with through-bolts running through the spar.

The U-bracket has a problem with cracks in both the Cruisemasters and Viking series of aircraft.  Typically this is because the spar through-bolts are over-tightened as the wood in the spar tends to shrink slightly with age.  The over-tightening crushes the spar wood and pulling the U-bracket sides closer together.  This results in cups being smashed into the U-bracket faces under the bolt heads and nuts, and also results in cracks along the U-bracket bend radii.  Over time these cracks can results in failure of the part which will cause the landing gear leg to fold up upon landing.

There is an AD issued for the U-bracket cracking problem on Vikings, but this AD doesn't seem to apply to Cruisemasters.  Nonetheless I'd suggest inspecting this part.  The fix, if the part is bent, is to carefully inspect.  If cracks are already apparent in the bend radii then replacement is called for.  If the part is not cracked, you could hammer the cupped bolt holt areas flat and reinstall with 4130 flat shims on the inside of the U-bracket area to make up for the wood spar shrinkage.