TackleTour

I have an older ch-100a with a left side plate turn key dual that won't budge. I'm afraid to put to much torque on it because it might break.
What's the best way to get the turn key dial to turn so I can get the left side plate off.
It the original silver chronarch 100a.

Spray a penetrative spray in behind the spool, and back off the cast control right off to get a small gap, get it in there and allow to penetrate for a while...

I snapped a Curado B key turn because the side access cam screw were slightly corroded into the frame, didn't use penetrative oil but Salt Away which didn't do the job unfortunately...

Why its important to lube up those old screw in side plate accesses and even the newer lugged side plate access hatches a little with Lanolin or similar to to prevent it sticking in the future.

Use two wooden rulers to apply greater pressure to the turn key rather than just your fingers, trust me turn slowly.

Some of the guys in Texas used to dip the side into boiling water over and over again for short periods of time. They had great success doing that.

Shimano makes a wrench that fits this turn key dial, BNT2390. I have one that came with the old gold Chronarch or MG, can't remember which.

Works a treat, and never damaged a dial using this.

Sure Dan can advise.

Had to spray it with WD40 over and over and let it sit for several days.
Finally got it off but not without chipping part of the turning tab off.
There was some rust on the brake race but I didn't see any corrosion on the threads for the side plate turn daily. Sanded the rust off and cleaned the side plate threads off.
I did manage to super glue the broken piece back on to the turning tab so it doesn't look too bad.
But in the process, the small spring in the turn key dail flew off into eternity somewhere. I had to cut an extra spring I had from another project to fit. Seems to work fine though.
Thanks for everyone's input.