Well, assuming that 171 is the same as 0171 in newer remotes, then this is Emerson protocol, device 41. But if that is true, then any silver Comcast remote should work using 0171
If the Comcast remote has a red Select/OK button use 10171 instead. For the red button remote, also try 11271.

Probably the RCA rcu 800 would work with 0188.

Please check these setup codes to try to verify if we have the IR protocol correct. If it is, there are a few codes we can try. At the worst, we can try all 256 combinations of the individual button codes and map out the TV.