Any fix for a locked groove?

I assume a 'locked groove' means the stylus kept repeating the same groove on every rotation.

Some causes:
1) A warped record causing the tonearm to skip back into the same groove on every rotation. Might be fixed by slightly increasing stylus tracking force.

2) Particulate in the groove. Identify the physical position where the stylus skips and then inspect with a magnifying glass. Sometimes the particulate can be carefully removed.

3) Bubbles in the vinyl due to a bad pressing. Try increasing the tracking force.

Hope this helps,

Relax, have a Stone Brewery Old Guardian and listen to some Armageddon...

Are you SURE its the records? 5 ,all towards the end of side 2?? .I think it may well be your arm setup. Sounds like the arm is reaching the end of it's travel before the end of the record

What kind of TT and TA do you have?

If I leave my dustcover on, I get a "locked groove" every time (when my tonearm bumps into it).

If my tone-arm SME V is sufficiently low set-up for VTA, some slightly warped records touch the arm close to the thick end of the arm tube when the needle is in the last 1/3 - 1/4 of the LP. This lifts the arm out of the groove with every turn and again = "locked groove".
Solution: use a higher (taller cart to go up with the arm for same VTA, use cart with more positive VTA requirement, clamp the record a bit harder to flatten it some more, if it can be done, don't play warped record, use tone arm with thinner arm tube, etc.)
Greetings,