read the horizontal yoke using an lcr or inductance meter
0.900mh to 1.6mh is 15khz
0.300mh to 0.400 is 25khz(some run 0.600mh)
0.100mh to 0.200 is 31khz
otherwise find the chassis model number,if you do not have the chassis model then you can only id using the above process