This Canon 25 came to me with some problems.  Maybe you would like to see what I have done with it.  First, I must remove the top plate.  I must unscrew the collar screw which holds the winding/cocking lever on:

I use a piece of rubber hose.  You can also use tape which is sticky on both sides.  You need something which will give you a grip, but will not scratch the piece.


There are trim screws, and there is also a screw which covers the vertical rangefinder adjusting screw.  You can unscrew this, but we will not need to.  You can see it here:

 

After I remove the cocking/winding lever, I will block the film fork and unscrew the rewind knob.  Remove any screws beneath them and all trim screws and remove the top plate.

The first problem with the Canon:  the meter did not work.  I think you can see one obvious problem if you look below.  For some reason, the shaft of the meter did not fit into the slot any longer.




 


It is easy to repair this.  You can also see the adjustment resistor for the meter up here on top. 



Ok, now the meter will work better I think.  In this camera, the rangefinder was ok for infinity adjustment, but the viewfinder was very dirty and foggy-looking.  Also, the vertical adjustment of the rangefinder is out of adjustment.  Let's fix that.  Remove the 2 screws to gain access...


When you are inside, you can clean the glass as shown below.  Please be careful with the diagonal glass.  This is sensitive, and you do not want to damage it.  I am using a Q-Tip (Cotton Bud) or whatever these are called where you live.  You soak the tip with a good glass cleaner and wash the glass.  Use the dry end of the Q-Tip to dry it.

 
Also in this camera, the film counder did not work.  You can see why if you look below.  The little arm is bent and the film door does not make the lever move in and out.  I wonder how so many things were broken in this camera.  This is not difficult to repair.  Open the film door and bend it downward.


The vertical rangefinder adjustment is not difficult.  You can see the screw which will adjust it below.  Once you have this adjusted, a paint dot will keep the screw from turning.  You can also use fingernail polish or white glue.  Anything will hold it.

 
Before we finish in the top area, one of the strap lugs was loose.  Here is how I will make it tight:


In this camera, the shutter was ok, but the aperture blades were sticky.  Even though the meter was working now, the blades were so sticky that it seemed like the meter was bad.  So, I will remove the rear lens element and clean them with solvent (like naphtha or mineral spirits or 100% alcohol).  Naphtha is very good for this.

 
For this, I will use a special tool I have made with a pair of pliers and a file:





The glass looks good in this camera...


I hope this is helpful.  When the shutter blades are clean and very dry and working ok, then you should replace the rear element.  Clean the glass first, especially on the inside part.