Hello and thank you in advance for any help or advice. I had a mechanic replace the shift mechanism (Dorman 905-101 Column Shifter), which he completed, but now it won't shift down into first. It otherwise goes into park and reverse correctly, and it seems to shift through all the gears. It simply won't allow me to manually shift down into first. Frankly, I haven't shifted into first for years, so I can't say for certain whether it was a problem when I took it in.

I replaced the shift mechanism because the attachment plate was cracked. (It was drive-able with the old shift mechanism.) Is this issue simply a matter of adjustment, the wrong part, the wrong mechanic, or something worse? Thank you.