Hud Display problem

[CDUB]

After driving my 2005 xlr for about 20 minutes my HUD just drops down to a low part of the windshield and I can not raise it back up for aboiut 10 minutes. Does anyone now what can cause this?

 

[MPRCTCL]

Mostly a guess, but I took one apart once and there is a spring that pulls a mirror on its pivoting mount. The one I looked at, the spring had rusted and broke.