According to TERMCAT:

joc

ca joc, n m
es holgura
es juego
fr jeu
en clearance

<Enginyeria industrial > Enginyeria mecànica>

Espai entre dues peces muntades que permet el moviment de l'una respecte a l'altra.

That is, the part was so worn out that its fit had become too loose. Other than that, there was no fault and the problem was solved by just replacing the part.



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Note added at 1 día4 horas (2012-05-02 19:50:28 GMT)
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If the part was "gastada", that is, worn out, I see no other possibility although, certainly, adding that "a la qual fallava el joc" instead of (for instance), "que tenia massa joc" makes for confusion. However, if the preceding word, "gastada" is considered, then the point is that the part was too loose without any ambiguity, and this means that it was "loose" (if "worn out", I cannot imagine the opposite, that is, that it was too tight).

And also, given the above quoted definition of "joc", it MUST be a part of an assembly/subassembly which could be called a "set", but what matters here is that this SINGLE part was causing the malfunctioning of the said set, hence the problem is its being too loose (cause) which entailed the malfunction of the set (effect).

That's why I am sure that "joc", here, translates as "clearance".