sources.list for debian alpha

Hello all,

My debian alpha box was off for a long time (over 2 years).
When I turned it back on a few days ago and tried to update, the keys had expired so I got a new one and started updating.
apt reported several packages had to be deleted (cinnamon amongst them).
So my alpha debian box runs mate now.  But I believe I'm not getting many of the updates.
The framebuffer seems very slow now compared to how it was working before it went on "vacation".  I remember several xserver packages were among those listed for deletion.
Hardinfo GPU test now takes forever.
Tried to download the firefox-esr 52.6 but it was "not found".

Does anyone have a sources.list file example for debian alpha?
The machine is a DS15.
Thanks in advance.