6. (10 points) There is a batch of machines, a total of 500 units, each using 6 of the same type of part. Parts that fail within a week must be replaced with new parts by the end of the week. Of all new parts, 10% fail by the end of the first week, 30% fail by the end of the second week, and the final 60% fail by the end of the third week; no parts can last beyond the fourth cycle. Therefore, the number of new parts needed by the end of the third week is $\qquad$.

将上面的文本翻译成英文，请保留源文本的换行和格式，直接输出翻译结果。
【Solution】Solution: According to the analysis, the total number of parts at the beginning is: $500 \times 6=3000$ pieces, at the end of the first week, $10 \% \times$ $3000=300$ pieces are scrapped,
at the end of the second week, $30 \% \times 3000=900$ pieces are scrapped, and at the end of the third week, $60 \% \times 3000=1800$ pieces are scrapped, as shown in the table below:
\begin{tabular}{|c|c|c|c|c|}
\hline & Start & End of First Week & End of Second Week & End of Third Week \\
\hline Initial number of parts & New 3000 pieces & 300 pieces & 900 pieces & 1800 pieces \\
\hline New parts replaced at the end of the first week & & New 300 pieces & 30 pieces & 90 pieces \\
\hline New parts replaced at the end of the second week & & & New 930 pieces & 93 pieces \\
\hline New parts replaced at the end of the third week & & & New 1983 pieces \\
\hline
\end{tabular}

From the table, it can be seen that the number of new parts replaced at the end of the third week is: 1983 pieces.
Therefore, the answer is: 1983.