Acceptable GRE scores for a midrange masters program?

Ouch,

for engineering masters, you want a better quant score than that.

I don't know about other universities, but Northeastern and Vanderbilt are highly selective.

I would just apply it since your major GPA is great and have some research experiences. Schools start to consider less weight on GRE, so you may want to apply couple more schools of your choice.

If you have a PI who'll write a letter of rec, and s/he knows some faculties from the schools of your choice, ask him/her to introduce yourself to that faculties and send your interest of the program via e-mail or mail or visit their office.

Believe it or not, professional network play a great role in school admission.

Don't retake GRE, and apply the program asap. deadline is approaching fast.

Good luck.

I would call up the admissions office or email them and ask them.

The GRE is a test that predicts how well you might do in graduate school. I think most graduate schools would have to have rocks in their head to not accept someone who has a 3.9 major and research experience.

I don't think it is worth taking again.

I think that you might be in demand, as a student wanting to get a masters in mechanical engineering, so I don't think the test scores are as important.

I'm also glad you are pursing an education that will make you more marketable. Graduate degrees in the humanities and social sciences are not helping people get jobs right now.