The glass of the Telrad is rather a dew magnet.
To reduce this I have used these anti-fog wipes and built a dew shield made from an A4 sheet of black foam and some velcro cut into small squares.
It is very easy to make and the details for doing this are below.
My Telrad on my Meade 10″ Dobsonian will not show anything when turned on, is it burned out? Is it worth buying parts to fix, and where can I get parts in Canada?
The variable resistor does need to be turned to maximum to check it is working. They do not illuminate when initially turned on.
Make sure the battery holder terminals are clean and that the batteries haven’t corroded – they last a long time! Your head/eye needs to be in the correct position to see the red reticle on the glass window.