Glacier Bay Coal Stove Insert grate mechanisim

[Glacier Bay]

I am the original owner of a Glacier Bay insert that I purchased in 1980. I absolutely love it and it has kept my home warm for the past 29 years. I have all the original paperwork but unfortunately it does not show the grate shaker bar on the drawings. I am having a problem with the connector bar for the 5 shaker grates. It fell off last week and when I looked underneath I thought it was free floating between the 5 grate bars with the center grate being the balance where it just sits on the pin on the grate bar without cotter pins or anything else securing it. I repositioned it on the center grate with the alternating side grates positioned on the remaining 4 pins. I shook it several times and all the grates seemed to work perfectly in unison. I started the fire up again and when I went to shake the coal down the bar fell off again. Anyone have any ideas? Thanks