So to bring some additional clarity to the situation...
-The park are awaiting a part. This is evident by the fact staff aren't working on it actively. This means it'll be closed a while. Even when the part arrives, they will require time to test it.
-It is likely a bigger / more expensive / specialist part, hence why the park didn't have one already. This takes time to acquire; it's not like they ring up Intamin and say "Can we have 1 [thing from catalogue] please?" and Intamin ship it out the next day from their warehouse either.
-Time frame is unclear at the moment. How long is a piece of string.
-Thorpe have no intention of getting rid of Stealth.