CalComp Technical Support states version 1.9a of their software will work with System 7.5.3 if the CalComp software is reinstalled after upgrading to 7.5.3.
However, CalComp Technical Support recommends upgrading to version 2.0. It is available on their ftp site,
ftp.calcomp.com
or on their BBS, 714-236-3045.
On both locations, the file name is "adb20a.sea".