Neje master 2s homing fail

I haven’t used the 2s for a while, and in the interim the software has moved on

my last available upgrade is 1.2.04, but prior actual work had been done on 1.2.01, which was working fine

i updated to 1.2.04 because trying to use a file created on that version on my desktop machine threw a message suggesting it may not work properly on the older version that is on the laptop that connects the neje in the workshop

the available working size is set at x=170mm, y=155mm, to accommodate a larger laser module (NEJE N40630 laser module) which worked well on these parameters without binding on limits
origin is defined as left front, as previously also
but when i try to have the module move to home, the mount hits the upper left limit

and the following appears in console-

ALARM:9
Homing fail. Could not find limit switch within search distance. Defined as 1.5 * max_travel on search and 5 * pulloff on locate phases.
how do i reset home?
i did it ages ago via console i think, but have long forgotten how, because until now it just worked perfectly
the constant grinding up against the limits on “return to home” is as grating as the sound it makes
help please!