Shimano Calcutta 251. Spool release button issue and more.

[Fishgolfman]

I must be a sucker for reel deals. Got 251 calcutta that button wont depress. Figured it was a yoke problem but i can mechanically move and turning handle to engage. The reel is missing a side plate screw , bearing and pawl cover is cracked. All easy parts to find. Seems that the post on button cannot reach and depress the yoke system. What part do I need to find?Enclosed is a schematic and pictures of reel