Its probably the coil. It sticks out like a sore thumb. The transformer has a shield around it.
Most likely the CTC-88 coil will work. The chip used is an RCA CA3071. It was also manufactured by Motorola as the MC1371. It was part of a very popular chipset:
http://www.ralphselectronics.com/pro...EMI-CA3071.PDF
The manuals are assembly for the most part and since yours is already assembled, they're not needed. The schematic is a large 24x30 sheet.
BUT that set is legacy technology so you shouldn't need a schematic.