Miller LMSW-52 Owner's Manual page 18

Trouble
Longer than normal weld time required.
Burn through at point of weld.
OM-716 Page 14
Clean ends of tongs and tong holders (see Section 3-2).
Check power switch (T models only) and/or start switch. Replace if necessary.
Dress or replace tips (see Section 3-1).
Clean workpieces.
Adjust tong pressure (see Section 3-3).
Clean ends of tongs and tong holders (see Section 3-2).
Check input line voltage.
Shorten weld time (see Section 4-1).
Adjust tong pressure (see Section 3-3).
Dress or replace tips (see Section 3-1).
Realign tips (see Section 3-2).
Remedy