My iMac’s screen showed yellow vertical stripes and the boot process would not complete.
Spread over two days, the repair process was tedious, but thanks to the iFixIt guide and especially a few of the added comments on missing steps, transposed descriptions of connections, etc., it was ultimately a great success! So good to hear the start up bong and to see a clear image of my desktop.
There were some illuminating comments in the guide (e.g., the Airport card connectors were described backwards, the ODD cable connections to the logic board were omitted). Also, as per one of the comments, the suction cups are not necessary, but they do work well.