  We investigate a non-perturbative vacuum in open string field theory expanded
around the analytic classical solution which has been found in the universal
Fock space generated by matter Virasoro generators and ghost oscillators. We
carry out level-truncation analyses up to level (6,18) in the theory around
one-parameter families of the solution. We observe that the value of the vacuum
energy cancels the D-brane tension as the approximation level is increased, but
this non-perturbative vacuum disappears at the boundary of the parameter space.
These results provide strong evidence for the conjecture that, although the
universal solutions are pure gauge in almost all the parameter space, they are
regarded as the tachyon vacuum solution at the boundary.
