He is willing to trade, isn't he? I would, too, if I were him. If I were you, I wouldn't consider this deal. If you want a 574 with problems, buy one and keep your WD-45. According to my blue book, a high vale trade-in on a WD-45 is $1200. This 574 would need to be considered below average. Trade-in for an average 574 is $1700, below average about $1000 or less - perhaps as low as $700.
On the other side, a really top 574 is worth more than a really top WD-45 on the retail market.