StuartMac put it well: "The '71 650 parts book "TR6C HEADLAMP" pages are confused".
As correctly listed in RPC 99-0932, TR6's use a rotary on/off lighting switch: Lucas PN 31276 (99-1211, Ref.15 in Fig.31 and P.79 parts listing).
However, the RPC 99-0932 parts listing on P.81 gives Lucas PN 31272 for the TR6C's 3-pole lighting switch. StuartMac notes that Lucas 31272 is actually a push-on/push-off dip switch for "much earlier twins". He tells us the correct Lucas PN for the 3-position 99-0563 lever switch can be either Lucas 35710 or Lucas 31788.
Good to know.
Also, while the TR6C's lighting switch is shown as Ref.21 in Fig.32, it appears as Ref.19 in the parts listing on P.81.
The TR6R uses a 4-position combined ignition-and-lighting switch in the sidepanel. StuartMac informs us that the original Lucas 39565 (99-1200) switch is superseded by Lucas 30552 (99-7055).
Go to RPC 99-0932 Error #100535
Go to RPC 99-0932 Error #100536