Before the final testing of voting or counting machines for any election, the general registrar shall mail written notice (i) to the chairman of the local committee of each political party, or (ii) in a primary election, to the chairman of the local committee of the political party holding the primary, or (iii) in a city or town council election in which no candidate is a party nominee and which is held when no other election having party nominees is being conducted, to the candidates. The notice shall state the time and place where the machine will be tested and state that the political party or candidate receiving the notice may have one representative present while the equipment is tested. At the time stated in the notice, the representatives, if present, shall be afforded an opportunity to see that the equipment is in proper condition for use at the election. When a machine has been so examined by the representatives, it shall be sealed with a numbered seal in their presence, or if the machine cannot be sealed with a numbered seal, it shall be locked with a key. The representatives shall certify for each machine the number registered on the protective counter and the number on the seal. When no party or candidate representative is present, the custodian shall seal the machine as prescribed in this section in the presence of a member of the electoral board, the general registrar, or a designee of the electoral board or general registrar.