This increases the electrode gap, which can adversely affect laser performance. To compensate for this normal wear, the adjustable electrode must be moved. With SG1 disassembled, measure the distance from the electrode tip to the bracket. If it is less than 20 mm, the tip has worn and must be adjusted in order to maintain the factory setting of 2 mm. The adjustable electrode will eventually wear to the point that it must be replaced.
Contact PTI to obtain a replacement.
There are ten screws which hold it shut. It is hinged at the back. After removing the screws, lift the lid up and back. The surfaces of the electrodes will normally darken in time as deposits are left on them. Only when they are excessively blackened do they require cleaning.