Problem Updating 12.04 to 14.04 on Lenovo Thinkpad Using update-manager -d

[mlnease]

Hello,

My wife's trying to revive her old Thinkpad which was running 12.04. I'm trying to upgrade it to 14.04 using
update-manager -d; this seems to be working fine, then consistently fails with numerous 'failed to fetch' error messages. The network is fine.

Any suggestions, anyone?

Thanks in advance.