‘In 1655, M. Trevenot brought ropes with him and describes the experience of a Scotsman who was lowered down the Well Shaft. He said ‘The Well was not entirely perpendicular; it went down about sixty-seven feet to a Grotto, from whence it again descended to a depth of one hundred and twenty-three feet, when it was sealed up with sand…’
Note no mention of the granite block.
In 1817, Caviglia manoeuvred the granite block – which was at that time lodged firmly in the Shaft - down into the Grotto, where it now resides.
Source: Henry Salt. Life and Correspondence. Pages 65 to75. 1834.
This suggests, does it not, that this granite block was thrown or lowered down the Shaft some when between 1655 and 1817?
For greater details on these four blocks of granite and (IMO) a stronger argument for their being the remains of portcullis blocks, see ‘The Egyptian Pyramids – A Comprehensive Illustrated Reference’ by J. P. Lepre. Pages 89-92. 1990.