help

well i have two questions for ya'll

1. my spedo was geting stuck at 40 so i took it out and re greased it then put it back in, took it out did the same thing. i thought i didnt get it in all the way so i tryed it again and same thing, so my question is what do u think that the problem is?

2. my defoster vents are cracked and broken and i bought some new ones and is there any way to put them on with out taken the entire dash off? if there is can u explain it to me please.

thanks,
mickey