I am new to CNC so bear with me please.  I have a small, old 3 Axis router running Mach 3 through UC400 Ethernet board to 2 Mach 3 break-out boards - the cheap generic ones.  It all seemed to be working well but now the Manual Override button is flashing red - I cannot home the axis and the limit/home switches do not work (proximity type).  When I jog to the end of travel it just hits the hard stop - fortunately very slowly and EStop works fine!  Previously I was able to Ref All Home without problems.  I have tried switching off the Auto Override, disabling and reenabling the homing and limits in Ports and pins, but to no avail.  I cannot de select the Manual Override button - just keeps flashing red.  As you will now realise I am very much a novice and I would welcome any help please.
Thanks Mitch