This is
a common problem for the reflex series. The needle itself can 'stick' to
one side. This is typical after 50+ years of dirt and grime. If the camera is
used in a smoking environment, cigarette tar can also contribute to the
problem. The needle actually 'sticks' to the plastic stop(s) on either side the
galvanometer.
Next time it happens, try rotating the ASA dial all the way in one direction and then the other, and finally back to your normal ASA setting. If the needle was stuck, this will usually dislodge it. The permanent cure is to remove the eyepiece diopter, and very carefully, clean the sides of the needle with a small swab soaked in alcohol. If you can see a 'fuzzy edge' on either side of the needle, through the diopter, the needle absolutely needs cleaning.
If rotating the dial may temporarily "cures" the problem. The permanent fix is to clean the sides of the needle. You can do this. Here's how:
Next time it happens, try rotating the ASA dial all the way in one direction and then the other, and finally back to your normal ASA setting. If the needle was stuck, this will usually dislodge it. The permanent cure is to remove the eyepiece diopter, and very carefully, clean the sides of the needle with a small swab soaked in alcohol. If you can see a 'fuzzy edge' on either side of the needle, through the diopter, the needle absolutely needs cleaning.
If rotating the dial may temporarily "cures" the problem. The permanent fix is to clean the sides of the needle. You can do this. Here's how:
CLEANING
THE BOLEX REFLEX LIGHTMETER NEEDLE
1) You need: denatured alcohol or vodka. Very small amount - an ounce or so, just enough to wet a small cotton swap, like a Q-tip (http://www.qtips.com/).
2) Unscrew the diopter. It turns counterclockwise. It's on tight but you can usually remove it by hand. Once its loose, be sure not to loose the extremely thin adjustment rings. There may be as few a one or as many as 3 rings. They are black and almost invisible. Very easy to loose. The rings are used to make the initial adjustment matching the diopter to a 'relay lens' inside the body. Put these pieces to the side.
3) Rotate the dial to the smallest ASA setting by turning it counterclockwise as far as it will go. This will place the needle all the way to the left side.
4) Using a Q-tip (http://www.qtips.com/) or any other small swab, soak it with the alcohol or vodka, and very carefully, clean (see next) the side of the needle thru the diopter's threaded opening.
5) Carefully touch the top of the needle and brush from the top of the needle downward to the bottom with a very light pressure. Do not brush in / out! Do not brush upwards! The Q-tip can snag on the needle if going upward or bend the needle if it goes in / out. Repeat several times.
6) With the one side finished, remove the swab, rotate the ASA dial fully clockwise. This will move the needle to the right. Soak the unused side of the Q-tip or swab, and again, brush the needle as above. Top to bottom as before. Repeat several times.
7) Reinstall the diopter - don't forget the rings.
If this is successful, the needle will no longer stick to the meter stops at the sides. If it still sticks, the meter stops will, most likely, also need to be cleaned. Trained personal can usually reach the meter stops from the side and clean them. If not, the meter (galvanometer) will need to be removed for cleaning.