hifi engine

Technics RS-1700 Reel to Reel deck

Unit has no output right channel in fwd. mode, left channel ok. Reverse mode is ok
in both left & right channels. Pull head block, clean/de-oxit head & tape connections,
pins, ect. This seem to work, but only temporarily. Sometimes the right channel will
start to play ok in fwd. mode after tape runs and hour or more. The "right" channel
playback amp on main pc board is "commom" to both "foward" & "reverse" right
channel playback heads. Per schematic, I suspect the head select relay may be bad
intermitting. Relay RL101 and/or it's associated parts, diode D109, capacitor C157
(0.047ufd)any trace, wire, solder joint between select relay & input to right channel
playback amp is suspect. I'm making the assumption, the Fwd. right channel playback
head & it's connection up to the select relay is good. Verified my headblock works ok
in another technics deck. Has anyone else experience this or similar playback issue
with a Technics RS-1700 reel to reel deck. Donald K. Jones (ex, USCG Loran C Tech.)