There's not much to go wrong and running at low power means they are unstressed.
I'd check the usual:
-So is it complete? Especially the correct diopter and front sight. [Barrel weight/shroud would be a very nice, but unusual, find].
-Make sure it has the correct Rekord trigger unit, it's not unheard of for them to be replaced with the standard unit.
-Stock check for cracks, barrel for straightness, and breech lock to ensure it does it's job.
-If in good condition it should cock and shoot smoothly. Velocity should be in the mid-high 600's
Here's some HW55 porn for you, courtesy of Mr.Driskill and the AVA forum.
Having been in production for so long there are numerous detail changes and more than a few separate models (There are some early pre-Rekord trigger unit guns for example).HTH