Original WWII German replacement 8cm Gr.W.34 mortar parts. Many parts are still partially coated in a red sealant to provide corrosion protection. The coating is original German also.
This is the screw that adjusts the barrel right and left. If yours is bent or damaged, it will make traversing very difficult. There are a few other things that could also make it difficult, but this is one of the possibilities.
Parts are in great condition. Markings may vary; some parts have no markings. Only 3 available - no hope of ever finding more.