Hey Nelly,
So, I can speak a little to your situation - as mine was similar. From what I know about technical writing in health care, many of those skills probably overlap with that of an RA. If that is the case, make sure you showcase those skills in an application.
Additionally, if you are still in healthcare, check and see if there are any research opportunities join, even if just a part time contribution. I understand adjusting to an RA salary might not be doable, but there are other ways to get experience.
I'm assuming those lower grades are 15+ years old....while I can't predict exactly how ad coms will feel, I wouldn't worry so much about those as much as getting the strongest qualifications now.