I bought a used trombone but the slide was hanging so I had it repaired (slide reconditioned). The slide moves freely now but is a little noisy (shh, shh) and feels the slightest bit gritty at portions. This is my first trombone. Is this normal? Freshly oiled, still happens. Obviously I can still practice with it, but I'm wondering if the repair job went as should be expected or if I ought to be worried about doing damage to the slide by using it like this. Thanks for any help.

Sounds as if the inside of the tubes haven't been cleaned completely. Take it back & complain.