The International Cessna^® 170 Association

I have a problem with the knob on my primer spinning. It makes it difficult to lock/unlock the primer. Is there a fix for this? I cant figure out how the knob attaches unless it is pressed on.

I had a similar problem and the knob is threaded on and I used super glue to hold it on But after a about 18 months the knob cracked and fell apart. I tried buying one , nobody could supply a knob so a washer was soldered onto the shalf with a nut and the whole built up with heat shrink to protect against sharp edges. Works just great. I could have bought a completely new unit from Spruce for Mega bucks.

Our original knob is long gone. Replacement knob is glued on with JB weld.

I'd use "Super Glue" (cyanoacrylate). You can find this at hobby shops in a thicker viscosity that cures in about 60 seconds which might fill the gaps and give you the time you need to properly place/thread the knob back on. A 5 minute epoxy would also work.

Maybe my threads are striped then. My know just turns in place. I can't pull it off.

If you can't pull it off then I'd use this "super glue" Let it wick between the knob and the shaft.

I'll give that a try. I have some CA.

Drill and "pin" it with a roll-pin.

I would not drill and pin it. First you are likely to get an oversize hole in the knob as the plastic way melt. Second I think it likely the 70 year old plastic knob will likely split at the drilled holes.

Bruce Fenstermacher wrote:I would not drill and pin it. First you are likely to get an oversize hole in the knob as the plastic way melt. Second I think it likely the 70 year old plastic knob will likely split at the drilled holes.

I agree. My advice is not appropriate for a plastic knob. I had not recalled it was a plastic knob, I had to go back and look at the pic.

Just to close the loop on this. I ended up putting a couple drops of thin CA on it and letting it wick into the knob. SO far it has ben working great. No more loose knob.