Hi Hans,

 

The following scans show 12 ore 21 pos. 4 and 12 ore 22 pos. 4 ex the museum sheets, also 12 ore 22 pos. 4 ex my stamps and a 'detail' scan of the dot in the upper left frame which started to occur in 17.30 from c.100ore 6.

 

It looks to me to be the same frame used in 17.31.1 in pos. 6.

 

Regards,  Ed