Hi Sneaks,
I think the idea of a quote is to illustrate a point, to bring forward an issue that is interesting and hard to grasp with just academic writing.
Frequently quotes have been slightly adapted, for example leaving out short bits which are not relevant, not understandable etc. However, I think that the idea is to keep things as close as possible to what originally has been said. Also, if you would leave out bits, I think it is important that your co-authors agree with what you are doing.
:-)