what am I doing wrong with this blend door repair ??????

[z90sc]

.........followed dash removal instructions on here for my 98 LSC.........black (top) blend door arm was broken,removed broken arm and motor but new motor arm will not seat into blend door plenum. Have adjusted black arm btw hot/cold positions but no luck....what am I missing here? Any thoughts or ideas appreciated.
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[z90sc]

.......nevermind......fixed it....a piece of the arm was broken off inside the plenum, took a screw ran it up in there and pulled it out.......now I have heat. Just took a while to figure it out.