N2000 stack. SSH access broken

Hi have just updated the firmware on 1 of our 9 N2000 stacks to 6.2.6.6A07 but have lost SSH access.

Switch is working ok(and more importantly this latest firmware has a fix for our POE phones) apart from SSH.  Http and telnet remote access work fine.

I have already tried

console(config)#no ip ssh server

console(config)#crypto key generate rsa

console(config)#crypto key generate dsa

console(config)#ip ssh server

but still get the same issue.  putty (from multiple PC's and with windows firewall off) asked for username ,then password but after the password just hangs. another ssh program I use mobaxterm 8.2 reports a cypher error but I cant find any goggle hits for the message even on there own forum.

any help much appreciated.