Have you had any issues recently in which you've had to file either:
1) A payment dispute?
2) Unauthorised payment claim?
If 1, they could simply be looking into it.
If 2, filing this claim will always limit your account for a long duraton, if not permanently as it's a very serious matter as they consider you a risk of being hacked/people accessing your account without your consent.
Also, regarding the check. I assume you mean that $300 was deducted from your balance as soon as you requested the check to be dispatched. This is standard procedure to ensure you don't spend funds you've already requested to withdraw.
On another note, if your paypal is limited to a certain income range, then maybe you've surpassed it which has caused a limitation.
Lastly, are you limited for suspicion of money laundering? This has happened to me and many other gold sellers simply due to hundreds of transactions each month. I called paypal support and they removed the limitation instantly as soon as I explained what the investments and gross income was for.