I have a Bernina Active 125 sewing machine?

Question

i cleaned it and oiled it because the thread underneath was too loose and now when i start it it goes grrrrrrrr and will not sew

Answer 1

Sounds like you've got a thread snarl in there someplace.  Take out the bobbin case and check the race area and around the sewing hook carefully.  

Take off the needleplate and look around the feed dogs and anywhere else you can see for thread or lint.

Then carefully rethread (yes, from scratch!) with your manual in hand -- that alone will solve a large number of "won't sew" problems.

Answer 2

I think you have something caught in it, thread dust  or something.  If not you have moved the tension controls or the stitch length is too small.  You must have accidentally changed something when you cleaned it. Look in the user's guide for the  proper settings. If that does not work call the Bernina sewing machine company ask for customer service and they could troubleshoot the problem with you.