There may be a volume control limit that got turned on if you can only go to 80 whereas you had 99 before:
page 91 of the
manual says:
With this setting, you can
limit the maximum volume.
When the “Volume Display” se
tting is set to “Absolute”,
the “Maximum Volume” range is “Off”, 50 to 99.
When it’s set to “Relative”,
the range is “Off”, –32 dB to
+17 dB. To disable this
setting, select “Off”
In any case 80 should be close to "reference volume" and it's a logarithmic (dB specifically) scale, so a change from 60 to 80 is quite significant. Often its not recommended to even run a receiver above this level (no power amps involved?).