The 'a' is in Q 1. Wagner's emendation (Anglia, p. 523; 1879), "he's chang'd to melancholy dump," is futile.
ii. 62. Carved oút ⋀ like to the pórtall óf the súnne.
Pause for reflection. The ear is satisfied by the spondaic first foot and the anapæstic third. (With i. 11 and ii. 62 cf. A 2 above.)
vii. 3. For hé ⋀ troópt with áll the wésterne kíngs.
The rhythmical aposiopesis represents a rhetorical pause for which the strongly accented 'troopt' and 'all' compensate. Do., Dy., G., W., read 'troopèd,'—but I don't think Greene did.
x. 27. Contént ⋀ keéper; sénd her únto ús.
I have inserted a dash for the pause of decision after 'content': Lambert accepts the proposition and acts. No metrical stop-gap is necessary.
Sometimes the arsis is lacking, and is supplied by a pause or gesture:—
xiii. 4. Ah, Búngay, ⊼ my Brazen-head is spoíled.
A second 'ah' suggests itself, and Dy. and W. print it. But I have no doubt Greene intended the speaker to draw breath for a sigh indicative of despair.