problem with checkbox reset

Hello,

as described in the subject, i have a problem with a checkbox reset.
As you could see in the attachment, i created a form where a timer is working.
When the user pushes the STOP button, all fields should be cleared.
this is done by a function i created:
function stoptime()
{
var formatstop = new Date();
document.stoptime.stoptime.value = formatstop.toLocaleString();
document.getElementById(‘id_sc_field_linesrowid’).value="";
document.getElementById(‘id_sc_field_teamsrowid’).value="";
document.getElementById(‘id_sc_field_brandcode’).value="";
document.getElementById(‘id_sc_field_pochange’).value="";
document.getElementById(‘id_sc_field_processorder’).value="";

}

My problem now is, that i have to release the checkbox ( BC-Wechsel ) also, but i could not get it working !
I tried the getElementByID, getElementByTagName, everything i knew at the moment.

anyone with an idea to address the checkbox field so i could set:
document.getElement???(’???’).checked = false ?

thx

screenshot.1.png