Just bought a second hand iphone 5s 32GB for about £245, which is quite cheap here. Phone arrives and it is in fine working order apart from the cameras (both front and back) which have a substantial amount of dirt in the lenses. The front camera is the worst, images are very foggy from the amount of dirt. I use the front camera a lot for facetime, so I'd like to fix this. Is it easy to clean out the lenses or would I be better off sending the phone back? I've looked on ifixit.com but removing the front camera on a 5s seems quite a major job.