TCL Socket Help

Question

I've been trying to write a script that would telnet to another device to run some commands. Unfortunately, whatever I do, it seems I'm never getting past the motd banner. When executed, the script does open the session, and I get the full banner, but then it stops until the other device times out. I never the "Username:" prompt. Wireshark tells me the prompt is delivered, so I don't know what I'm doing wrong.
Help!
proc waitfor {sock pattern {delay 500}} {
  while { 1 } {
    after $delay { return -code error "delay expired" }
    gets $sock line
    puts $line
    if { [string match [string tolower $pattern] [string tolower $line]] } {
      puts "match"
      return -code ok
set host "yoink!"
set username "yoink!"
set password "yoink!"
set hostname "yoink!"
puts "Trying to connect to $host\n\n"
set sock [socket $host 23]
waitfor $sock "username:"
puts $sock $username
waitfor $sock "password:"
puts $sock $password
waitfor $sock "$hostname#"
puts $sock "show clock"
waitfor $sock "$hostname#"
close $sock

Answer 1

After some more tests, I found something odd.
Here's an output while running the script.
router#tclsh tftp://10.120.1.2/telnet3.tcl
Loading telnet3.tcl from 10.120.1.2 (via GigabitEthernet0/0): !
[OK - 811 bytes]
Trying to connect to 10.180.39.1
{^A{^C}^X}^_    <- Telnet negociation garbage
MOTD Banner Here!
Username:       <- There's a long delay (auth timeout) before this appears
                   And all following lines appear at once.  
step 2          <- Some debug
% Username:  timeout expired!
error reading "sock0": broken pipe
    while executing
"gets $sock line"
    (procedure "waitfor" line 4)
    invoked from within
"waitfor $sock "password:""
    (file "tftp://10.120.1.2/telnet3.tcl" line 28)
router#
So I did a manual telnet, and it looks like this.
router#telnet 10.180.39.1
Trying 10.180.39.1 ... Open
MOTD Banner Here!
User Access Verification  <- This line doesn't appear in the script
Username:
So it seems this line is causing the script to bog down somehow.