Step 1: Since \( (x - a) \) is a factor, substituting \( x = a \) into the polynomial should make the expression equal to 0.
\[
a^6 - a \cdot a^5 + a^4 - a \cdot a^3 + 3a - a + 2 = 0
\]
Step 2: Simplify the equation:
\[
a^6 - a^6 + a^4 - a^4 + 3a - a + 2 = 0
\]
\[
2a + 2 = 0
\]
Step 3: Solve for \( a \):
\[
a = -1
\]
Thus, the value of \( a \) is -1.