Green’s Dictionary of Slang

dauber n.

also dobber
[? link to dial. dobber, a ‘wonder’]

(US) spirit, morale.

[US]Eve. Times (Grand Forks, ND) 6 Jan. 4/4: In the majority of cases two or three returns from the big show serve to get a recruit’s angora and his ‘dauber’ goes down.
[US]R. Lardner ‘Women’ in Coll. Short Stories (1941) 154: The boys were depressed. In their own language, their dauber was down.
[US]C. Willingham End as a Man (1952) 158: Don’t get your dauber up, let me explain.
[US]Randolph & Wilson Down in the Holler 258: keep your dobbers up: phr. To keep up one’s courage.
[US](con. 1920s) J. Thompson South of Heaven (1994) 117: He [...] told me to keep my dauber up.