SMC Takumar 28 f3.5

Picked up a SMC Takumar 28 f3.5 M42. All seems clean, fungus free, and with snappy blades and nice clicking f stops and half stops. Some very minor wear of paint in a couple places. Only thing is the Auto/Manual switch won't budge from Auto. Does anyone know if this is an issue or easily remedied?

Came with original case (no strap) and both caps. Anyone have an idea how much these usually go for, as this is my first Tak lens?

If the lens has a rotary lever on the mount for open-aperture metering, which an SMC one should, then it won't budge and shouldn't unless fitted to a stop-down metering Spotmatic.

The lens is intended for the Spotmatic F and the A/M lever is not needed except for earlier bodies. Don't try to force it, but fit it to a Spotmatic or Spotmatic II (or derivatives) and then it will move.

See your PM's

Probably worth writing this down here for the benefit of others though:

Auto-aperture Taks have a tiny pin (in addition to the pin that operates the aperture) on the rear that protrudes by about 1mm. When this pin is "up" (ie lens unmounted) it locks the auto/manual switch. When the pin is depressed (mounted on camera or adapter) the switch is free again. Never attempt to force the switch if the pin is in the up position or you'll break it!

I'd say yours would set you back somewhere in the region of £40-60 depending on condition

Forumers, I am ever grateful for all your wise directions.