[ESS] (Aquamacs) Why is text at R prompt read-only, cannot delete? 2

[Christian]

Hi,
Starting Aquamacs 3.3 on MacbookPro MacOS 10.12.6, I get an error
--------
Warning (initialization): An error occurred while loading 
‘/Users/hoffmannc/.emacs’:

File error: Cannot open load file, No such file or directory, 
~/elisp/vendor/ess/lisp/ess-site.el
-------

My /Users/hoffmannc/.emacs looks like this
_________________
;; ESS: Emacs Speaks Statistics
(load "~/elisp/vendor/ess/lisp/ess-site.el")

---> SORRY: it is currently:
(load 
"/Applications/Aquamacs3.3.app/Contents/Resources/lisp/aquamacs/edit-modes/ess-mode/lisp/ess/ess-site.elc")

;; Use shift-enter to split window & launch R (if not running), execute 
highlighted

... clip
            (local-set-key [C-down] 'comint-next-input)))
   (require 'ess-site)
_________________
..and the last line seems to cause the error, as can be seen by C-x C-e.
How can I correct this error?

Thanks for any hints.
Christian
-- 
Christian Hoffmann
Rigiblickstrasse 15b
CH-8915 Hausen am Albis
Switzerland
Telefon +41-(0)44-7640853