Quoted from ForceFlow:The rod has layer of powder coat, making the diameter larger.
The hole in the housing has a layer of powder coat, making the diameter smaller.
You have both made the rod larger and the hole smaller, which has compounded the problem of these two parts not fitting together properly.
About 25 years ago someone had sent around 'joke' specifications for piping. The very first one was, "1. Be sure when specifying piping to select pipes where the I.D. is smaller than the O.D., otherwise the hole will be on the outside". This thread reminds me of that...