any designs of an adjustable grommet handy?

[el-saturn]

hi everybody - i just made a sketch of a failsafe grommet tube which will get me back to a lathe for an hour or two. not the most comlicated engineering task, i know BUT I'm certain there's a bunch of lovely ideas - let's see 'em!! hope to see some intelligent solutions to a common TC problem. thanks sandy 36/4982
PS - i just saw a 26 chassis with a over 5000 number! 26/5000?? is that maybe teh reason mine is a 26 DHC with the wrong chassis number??