Section 5.1.  Eligibility for office.
   (a)   No person shall hold any elective office of the city, unless he was a resident of the city for at least one year immediately prior to the date of the election at which he is a candidate.  He must also have been a registered elector on the last day for filing nominating petitions for such office or prior to his appointment to fill a vacancy.
   (b)   No person shall be eligible for any elective or appointive city office who is in default to the city.  The holding of office by any person who is in default shall create a vacancy unless such default shall be eliminated within thirty (30) days after written notice thereof has been served at his last known place of residence by the city clerk upon the direction of the council, or, unless the officer contests his liability for the default in a court of competent jurisdiction.
   (c)   No person who holds or has held the office of councilman shall be eligible to hold any appointive office for which there is compensation paid by the city until one year has elapsed following the expiration of the term of office for which he was elected.  This provision would not apply to appointments where nominal compensation may be paid by the city.
   (d)   No appointive city officer or employee shall seek an elective office of the city unless he resigns his position with the city on or before the last date for filing petitions.