请教理解这两句话

下面一段是说明测量烙铁温度的步骤说明：
1) Check the effective term of calibration, because the measuring instrument should be calibrated.
2) Turn ON the power of measuring instrument, and then make sure that the same temperature
as the room temperature is displayed.
3) Turn ON the power of the soldering iron, and then wait for 2 min or more.
4) Remove the solder from the temperature-measuring unit by using the soldering iron.
5) Attach the soldering iron to be measured to the temperature-measuring unit, and refill 2.0 mm
of0.6 mm thread solder or 1.0 mm of0.8 mm thread solder.
6) Attach the flat part of the soldering iron to the temperature-measuring unit (soldering iron
angle: about 20̚30). Keep the position for 10̚15 sec, and make sure that the displayed
value stabilizes, then record such a value.
7) If temperature has been adjusted, repeat the measurement 2 min later, and repeat the steps
from the item 4) downward.

其中第4步和第5步没搞懂，请教一下：
第4步，测量温度的热敏电阻上没有什么焊料，怎么说移开焊料?
第五步，重新灌注锡是什么意思？

英语烂，请教大家，附图说明