[Makita saw cannot adjust height]

I have a Makita worm drive saw Model #.5007NB.  The plate will not lock because there is a bolt head on the locking adjustment mechanism that will not tighten.  Yjr lt heaad will not turn when I try to tighten it with a wrench.  How can I get this tight?

 

Thanks,

GB

[Makita saw not square]

I have a Makita circular saw Model # 5077B.  It recently stopped cutting square and now binds up even when cutting a 2x4.  I believe most saw you can adjust by a screw on the bottom of the plate.  This saw does not have a screw there.  How can I fix this so it cuts straight and square> 

 

Thanks,

GB