Hallo,
Ich verstehe die deutsche sprache nur ein wenig und etwas schreiben in Deutsch ist viel zu zwierig (?) fur mich aber when ich English oder etwas anderes schreiben darf…
Sorry something technical in German is too difficult for me , removing a starter on the other hand is fairly easy :
On a Fiat 1800 (77) it takes only two bolts , rather easy access from under the car, than removing from under the bonnet. ( 15 min ).
Before doing that make sure it is neccesary : as somebody already pointed out :check other things first
1/ good battery ?
2/ do you hear a click by starting ? yes/no
no : defect solenoid or no current to the solenoid/starter
yes : (some) current to the solenoid
3/ put the lights on : if you try starting is the light intensity lower?
yes/no
yes : there is current to the starter
no : no current to the starter
conclusion : try to start and look for a „click“ or not.
If not, check the electricity ( it’s more ‚electrickery‘ on a Fiat 😕 ) : cables to the starter, earth to the engine , and the ignition switch.
( I guess the problem is the ignition switch ( replacable)( I had that problem some years ago))
If you always hear a click , the starter/solenoid might be the problem.
I hope this helps (if not, give a shout )
Guten abend, Geert ( Damme, Belgium).