Declarer Play: Unblocking and maintaining entries

A number of situations involving Unblocking by declarer - including a Jettison Play.
Here are the links to hands we played:
This was played on Friday afternoon last year, but no one made 4S tinyurl.com/y997stmb
Similar problem - www.bridgebase.com/tools/hand... POLL2 what should North rebid?
tinyurl.com/y82hjy2m POLL3 How many likely top tricks do you have?
Need to unblock in hearts - as well as establishing the clubs tinyurl.com/ybpzuvpr
With few entries to dummy, you need to unblock ace of spades and then force an entry by leading clubs towards J 10 twice if necessary tinyurl.com/y9l3olst
After a spade lead you hope to make 9 tricks: 2 spades, 2 hearts and 5 clubs. tinyurl.com/y9cg7ss7 But the club suit contains a blockage: you must play 876 under AKQ or the suit will block and only 4 clubs can be made - Only 1 declarer made this!
Jetison
Once the ace of hearts is gone, you have no entries to your hand and because of ace of diamonds, the suit will block. The solution is to duck the first 2 hearts and jettison ace of diamonds on ace of hearts! tinyurl.com/yag5yjr5 - only possible if the opponents keep playing hearts.