First of all I am not an expert with fw's lol.
Looking at your rdr rule and comparing it with examples in The Book of PF, the rdr line itself seems right.
I believe rdr requires another rule passing the traffic as well. Which is what it looks like you are doing here.
Code:
pass in on $ext_if proto tcp to ($ext_if) port 32400 flags S/SA keep state
If it were me I would open this rule up and see what happens. I am not sure why you need the "to" part of the statement. And it seems to me that might be blocking any traffic not having a destination of em0.
Are em0 and 192.168.1.32 the same device?