Battery for the spotmatic

Hi, got my Spotmatic through the post recently and cant seem to get the lightmeter needle to work, I am guessing its the battery- tried an identical sized battery brought from Poundland (everything inside for a pound! sheeesh!) but this didnt make any difference.
Is there A particular type of battery I require or is the lightmeter defunct?

The PX400 Mercury cell (1.35v) is no longer available, but the Wein zinc/air relacement works fine. Cost is around £5.50 and it is obtaianble from Jessops or The Small Battry Company amongst others.

If you buy a Wein cell, activate it by removing the sticker and wait at least 30 minutes for it to start working properly.

If the meter does not seem to be working, make sure the battery polarity is correct.

If the battery you have came with the camera, it is quite possibly dead and in need of repklacement.

how do you check battery polarity?

The polarity simply means that the + and - poles of the battery should be the right way round.

Looking at the battery in its compartment in the base of the Spotmatic, the - should be facing you. In the Spotmatic F and subsequent Pentaxes of the K and M series the + should be facing you.

If you get it wrong, the meter won't work, so just swap it round!