By my reckoning Speed King, Child In Time (despite being 20 mins!) Paint It Black and Wring That Neck are all incomplete. I was surprised that this has never been a topic of discussion and wondered if anyone had any insight as to where the tracks came from (was it one of the videoing of Montreux gigs?) or why they have edits. Any I did think the notes that accompanied the box set made no mention of it.
I was wondering about these „edits“ too. I encountered things like that on various bootlegs/soundboard recordings (like Genesis live in Zurich, with a truncated version of Carpet Crawlers), quite often this happened because the tape/cassette was full or needed a flip. Montreux 71 comes from „offical“ sources (Swiss TV/Radio) so it is really dubious. Maybe their Revox Recorder was also running out of tape… or the recordings got somehow damaged. Funny no comment in the liner notes or any attempt to mitigate the issue somehow.
No idea, but there are several possibilities. The main one being that if this was a radio broadcast, the tape may have been edited to fit a certain programme length. The original tape may not survive as it was common practice to re-use audio and video tapes back then once a show had aired.
Next, we have the possibility that the sound was distorted at those points, and it was seen as better to cut than just have noise.
Then, as has been stated, the tape could have been damaged - either physically mangled, or the magnetic layer broke down/stuck to the tape layer below.