First Install new battery in battery compartment.

You may chose the battery you want. I sell the 625A 1.56Voltswich is an alkaline battery. For some the Alkaline battery is a poor choice. But it is a nice package that was produced to replace the 625 1.35 volts mercury battery and is readily available at most department stores and camera stores.

But the best choice is a silver oxide Battery such as the Eveready 357 1.6 volts.

Why this one. The voltage of a silver oxide battery remains constant until it is nearly dead where the voltage output of the alkaline battery drops off steadily from the time it is installed.

But what about the size difference? You can overcome the size issue by placing a rubber o-ring around the battery or you can slip the washer off of one of the wien zinc air batteries and place it around the new Eveready cell.

make sure your battery compartment is clean and install the new battery.

The metering system of the SRT is very simple. Consisting of a battery, CDS cells,   a couple variable resistors, a fixed resistor and a Galvanometer.

You can view the CDS cells as resistors as well that vary resistance with the amount of light that strike them.

The more light striking a CDS cell the less resistance to the voltage flowing through it. Thus the more voltage going to the Meter.

Under the bottom of the SRT there are 2 variable resistors that can be adjusted to compensate for battery voltage.

With the camera place on its back the top one adjust the light meter.

Use a know good light meter or a camera to take a light reading. Then from the same distance take a light reading with the camera you are adjusting.

If using a camera it is best to use the same lens on both cameras set for the same aperture and the same sutter speed. and also the same film speed. Distance and angle are critical.

Compare your readings. Then remove the bottom plate from the camera you are adjusting. Turn the resistor slightly and then place the bottom plate back on the camera to complete the electric circuit. Check the reading and repeat as needed to get the camera adjusted to the desired setting.

When this is accomplished. Turn the switch to b.c. to adjust the battery check. It is adjusted by the bottom variable resistor. Follow the same procedure as with the light meter adjustment to set the battery check as you desire. It is not critical as to where you end up with the B.C. reading but you want it to be able to show you if there is a substantial drop in voltage. With a new battery you may want it to push the meter to the bottom of the B.C. indicator and then replace when the Meter only reaches the top. But the main thing is to take note of where the meter reads with a new good battery.

When done replace the bottom plate and check your meter under a variety of conditions.

This should get your meter adjusted to where you want it.

Also there is an adjustment for the follower part of the meter under the top of the camera but rarely do you need to make adjustments to it. Most of the time only if the AV string has to be changed.It is adjusted by a cam screw under the camera top cover. If you take the camera top cover off be very careful not to let the camera come unstrung. It is a job getting those strings back were they go and around the right pulleys the number of turns that are required and in the right direction.

It is best to put the treaded washer that comes out from under the rewind knob back on as soon as removing the top cover.

Also when taking the top cover off it is important know that there is a screw behind the red dot on front of the camera. Remove the red dot with a needle and only replace the dot when you are completely done with the camera.

I try to use this as a quality control measure. Since when I get a camera I get it working clean and adjust it and then maybe days latter even after the sale do a final check of the camera adjust the meter then and replace the dot before shipping it out.