My glass cooktop is cracked and I've ordered just the glass cooktop surface to replace this in-counter downdraft model. I've also ordered the foam tape which appears to be the seal between counter and cooktop. I've done this on my own and need guidance on what I will encounter. This cooktop sits just above a cabinet with pretty good access below (it is a cabinet though). I need detailed instructions on replacement of this unit. I appreciate the help. Assume I know very little more than nothing. Thanks!