Vintage Lens repair

I've been learning some lens repair and I've come across a funny problem. I'm wondering if this has happened to anyone else.

The lens is a Meyer-Optic görlitz Oreston 1.8/50

The aperture blades were inoperable and I was able to tear the lens down and get all of the thick grease that was everywhere. I cleaned the blades as best I could and got it all back together. Here is the fun part.

The lens works fine when pointed down and most of the time when horizontal but if it is pointed upwards the blades will stick. Now I understand that gravity is playing a role however, maybe it's just a worn out and old lens that has some issues.

Anyone else have a lens they need to point down to get the blades to open?

Look for nicks or cracks in the blades? Especially cracks around the pivot openings? I've seen cracks at the openings that would engage and create problems intermittently. Maybe pointing in some directions your blades are able to work, and in others gravity brings a crack into a bad spot?

OK I don't see any cracks but there is a wave to some blades that looks as if they have been damaged very slightly. Over all the lens fires just fine it just doesn't always return to wide open which with my style of shooting will not truly be an issue. Its an M42 mount so it will likely be on a manual camera anyhow and I should notice in the viewfinder that it's stopped down when focusing. I can also clear the error by moving the aperture ring. All this will allow me to play with this lens as it. Time to move on and fix another lens.