Question about Old Viking Sewing Machine

I recv'd an old Viking machine(from someone who knows nothing about
sewing machines) which appears to sew just fine except for the huge (3
rows of 15 settings/bs LCR Manual) red selection stitch/embroidery?
knob which will not turn and will only allow normal stitch and zig
zag. I've tried to search for this model (1366) on the net, but can't
find any info. It looks like 1950's or 60's and has no style "name"
except for Viking.

Someone said it looks like an industrial grade machine, but it comes
in an old carrying case, so I don't think it is. It's light grey and
it also has a metal plate on the back which says Domestic Sewing
Machine Company, Cleveland Ohio, and Toronto, Canada. Is this an
embroidery machine as well as a normal sewing machine and is it worth
repairing the stitch selector device? Has anyone heard of this
particular model before? It's also got many more knobs and buttons and
sub-buttons and positioning levers which I've never seen on a regular
machine and it kind of makes it intimitading, but it does sew a normal
stitch and reverse just fine.